diff --git a/src/main/java/dev/zarr/zarrjava/core/ArrayMetadata.java b/src/main/java/dev/zarr/zarrjava/core/ArrayMetadata.java
index 03b2e85f..154d6692 100644
--- a/src/main/java/dev/zarr/zarrjava/core/ArrayMetadata.java
+++ b/src/main/java/dev/zarr/zarrjava/core/ArrayMetadata.java
@@ -43,6 +43,8 @@ public int ndim() {
 
     public abstract Object parsedFillValue();
 
+    public @Nonnull abstract Attributes attributes() throws ZarrException;
+
     public static Object parseFillValue(Object fillValue, @Nonnull DataType dataType)
       throws ZarrException {
     if (fillValue == null) {
diff --git a/src/main/java/dev/zarr/zarrjava/core/Attributes.java b/src/main/java/dev/zarr/zarrjava/core/Attributes.java
new file mode 100644
index 00000000..bc1cfe27
--- /dev/null
+++ b/src/main/java/dev/zarr/zarrjava/core/Attributes.java
@@ -0,0 +1,241 @@
+package dev.zarr.zarrjava.core;
+
+import dev.zarr.zarrjava.ZarrException;
+
+import javax.annotation.Nonnull;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+
+public class Attributes extends HashMap<String, Object> {
+
+    public Attributes() {
+        super();
+    }
+
+    public Attributes (Function<Attributes, Attributes> attributeMapper) {
+        super();
+        attributeMapper.apply(this);
+    }
+
+
+    public Attributes(Map<String, Object> attributes) {
+        super(attributes);
+    }
+
+    public Attributes set(String s, Object o){
+        this.put(s, o);
+        return this;
+    }
+
+    public Attributes delete(String s){
+        this.remove(s);
+        return this;
+    }
+
+    public boolean getBoolean(String key) {
+        Object value = this.get(key);
+        if (value instanceof Boolean) {
+            return (Boolean) value;
+        }
+        throw new IllegalArgumentException("Value for key " + key + " is not a Boolean");
+    }
+
+    public int getInt(String key) {
+        Object value = this.get(key);
+        if (value instanceof Number) {
+            return ((Number) value).intValue();
+        }
+        throw new IllegalArgumentException("Value for key " + key + " is not an Integer");
+    }
+
+    public double getDouble(String key) {
+        Object value = this.get(key);
+        if (value instanceof Number) {
+            return ((Number) value).doubleValue();
+        }
+        throw new IllegalArgumentException("Value for key " + key + " is not a Double");
+    }
+
+    public float getFloat(String key) {
+        Object value = this.get(key);
+        if (value instanceof Number) {
+            return ((Number) value).floatValue();
+        }
+        throw new IllegalArgumentException("Value for key " + key + " is not a Float");
+    }
+
+    @Nonnull
+    public String getString(String key) {
+        Object value = this.get(key);
+        if (value instanceof String) {
+            return (String) value;
+        }
+        throw new IllegalArgumentException("Value for key " + key + " is not a String");
+    }
+
+    @Nonnull
+    public List<Object> getList(String key) {
+        Object value = this.get(key);
+        if (value instanceof List) {
+            return (List<Object>) value;
+        }
+        throw new IllegalArgumentException("Value for key " + key + " is not a List");
+    }
+
+    public Attributes getAttributes(String key) {
+        Object value = this.get(key);
+        if (value instanceof Attributes) {
+            return (Attributes) value;
+        }
+        if (value instanceof Map) {
+            return new Attributes((Map<String, Object>) value);
+        }
+        throw new IllegalArgumentException("Value for key " + key + " is not an Attributes object");
+    }
+
+    public <T> T[] getArray(String key, Class<T> clazz) throws ZarrException {
+    Object value = this.get(key);
+    if (value instanceof Object[] && (((Object[]) value).length == 0 || clazz.isInstance(((Object[]) value)[0]) )) {
+        return (T[]) value;
+    }
+    if (value instanceof List) {
+        List<?> list = (List<?>) value;
+        @SuppressWarnings("unchecked")
+        T[] array = (T[]) java.lang.reflect.Array.newInstance(clazz, list.size());
+        for (int i = 0; i < list.size(); i++) {
+            Object elem = list.get(i);
+            if (clazz.isInstance(elem)) {
+                array[i] = clazz.cast(elem);
+            } else {
+                // Try to find a constructor that takes the element's class
+                java.lang.reflect.Constructor<?> matched = null;
+                for (java.lang.reflect.Constructor<?> c : clazz.getConstructors()) {
+                    Class<?>[] params = c.getParameterTypes();
+                    if (params.length == 1 && params[0].isAssignableFrom(elem.getClass())) {
+                        matched = c;
+                        break;
+                    }
+                }
+                if (matched != null) {
+                    try {
+                        array[i] = (T) matched.newInstance(elem);
+                    } catch (Exception e) {
+                        throw new ZarrException("Failed to convert element at index " + i + " to type " + clazz.getName(), e);
+                    }
+                } else {
+                    throw new IllegalArgumentException("Element at index " + i + " is not of type " + clazz.getName() + " and no suitable constructor found for conversion of type " + elem.getClass().getName());
+                }
+            }
+        }
+        return array;
+    }
+    throw new IllegalArgumentException("Value for key " + key + " is not a List or array of type " + clazz.getName());
+}
+
+    public int[] getIntArray(String key) {
+        Object value = this.get(key);
+        if (value instanceof int[]) {
+            return (int[]) value;
+        }
+        if (value instanceof List) {
+            List<?> list = (List<?>) value;
+            int[] array = new int[list.size()];
+            for (int i = 0; i < list.size(); i++) {
+                Object elem = list.get(i);
+                if (elem instanceof Number) {
+                    array[i] = ((Number) elem).intValue();
+                } else {
+                    throw new IllegalArgumentException("Element at index " + i + " is not a Number");
+                }
+            }
+            return array;
+        }
+        throw new IllegalArgumentException("Value for key " + key + " is not an int array or List");
+    }
+
+    public long[] getLongArray(String key) {
+        Object value = this.get(key);
+        if (value instanceof long[]) {
+            return (long[]) value;
+        }
+        if (value instanceof List) {
+            List<?> list = (List<?>) value;
+            long[] array = new long[list.size()];
+            for (int i = 0; i < list.size(); i++) {
+                Object elem = list.get(i);
+                if (elem instanceof Number) {
+                    array[i] = ((Number) elem).longValue();
+                } else {
+                    throw new IllegalArgumentException("Element at index " + i + " is not a Number");
+                }
+            }
+            return array;
+        }
+        throw new IllegalArgumentException("Value for key " + key + " is not a long array or List");
+    }
+
+    public double[] getDoubleArray(String key) {
+        Object value = this.get(key);
+        if (value instanceof double[]) {
+            return (double[]) value;
+        }
+        if (value instanceof List) {
+            List<?> list = (List<?>) value;
+            double[] array = new double[list.size()];
+            for (int i = 0; i < list.size(); i++) {
+                Object elem = list.get(i);
+                if (elem instanceof Number) {
+                    array[i] = ((Number) elem).doubleValue();
+                } else {
+                    throw new IllegalArgumentException("Element at index " + i + " is not a Number");
+                }
+            }
+            return array;
+        }
+        throw new IllegalArgumentException("Value for key " + key + " is not a double array or List");
+    }
+
+    public float[] getFloatArray(String key) {
+        Object value = this.get(key);
+        if (value instanceof float[]) {
+            return (float[]) value;
+        }
+        if (value instanceof List) {
+            List<?> list = (List<?>) value;
+            float[] array = new float[list.size()];
+            for (int i = 0; i < list.size(); i++) {
+                Object elem = list.get(i);
+                if (elem instanceof Number) {
+                    array[i] = ((Number) elem).floatValue();
+                } else {
+                    throw new IllegalArgumentException("Element at index " + i + " is not a Number");
+                }
+            }
+            return array;
+        }
+        throw new IllegalArgumentException("Value for key " + key + " is not a float array or List");
+    }
+
+    public boolean[] getBooleanArray(String key) {
+        Object value = this.get(key);
+        if (value instanceof boolean[]) {
+            return (boolean[]) value;
+        }
+        if (value instanceof List) {
+            List<?> list = (List<?>) value;
+            boolean[] array = new boolean[list.size()];
+            for (int i = 0; i < list.size(); i++) {
+                Object elem = list.get(i);
+                if (elem instanceof Boolean) {
+                    array[i] = (Boolean) elem;
+                } else {
+                    throw new IllegalArgumentException("Element at index " + i + " is not a Boolean");
+                }
+            }
+            return array;
+        }
+        throw new IllegalArgumentException("Value for key " + key + " is not a boolean array or List");
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/dev/zarr/zarrjava/core/Group.java b/src/main/java/dev/zarr/zarrjava/core/Group.java
index 5cff4774..b7cc83d8 100644
--- a/src/main/java/dev/zarr/zarrjava/core/Group.java
+++ b/src/main/java/dev/zarr/zarrjava/core/Group.java
@@ -83,4 +83,6 @@ public Node[] listAsArray() {
             return nodeStream.toArray(Node[]::new);
         }
     }
+
+    public abstract GroupMetadata metadata();
 }
diff --git a/src/main/java/dev/zarr/zarrjava/core/GroupMetadata.java b/src/main/java/dev/zarr/zarrjava/core/GroupMetadata.java
index 695bfdff..e7bd6ebb 100644
--- a/src/main/java/dev/zarr/zarrjava/core/GroupMetadata.java
+++ b/src/main/java/dev/zarr/zarrjava/core/GroupMetadata.java
@@ -1,3 +1,11 @@
 package dev.zarr.zarrjava.core;
 
-public abstract class GroupMetadata {}
+import javax.annotation.Nonnull;
+
+import dev.zarr.zarrjava.ZarrException;
+
+public abstract class GroupMetadata {
+
+    public @Nonnull abstract Attributes attributes() throws ZarrException;
+
+}
diff --git a/src/main/java/dev/zarr/zarrjava/core/Node.java b/src/main/java/dev/zarr/zarrjava/core/Node.java
index 0b511936..fbac2ba3 100644
--- a/src/main/java/dev/zarr/zarrjava/core/Node.java
+++ b/src/main/java/dev/zarr/zarrjava/core/Node.java
@@ -13,6 +13,7 @@ public interface Node {
 
     String ZARR_JSON = "zarr.json";
     String ZARRAY = ".zarray";
+    String ZATTRS = ".zattrs";
     String ZGROUP = ".zgroup";
 
     /**
diff --git a/src/main/java/dev/zarr/zarrjava/v2/Array.java b/src/main/java/dev/zarr/zarrjava/v2/Array.java
index 1cbfb056..e66c20e7 100644
--- a/src/main/java/dev/zarr/zarrjava/v2/Array.java
+++ b/src/main/java/dev/zarr/zarrjava/v2/Array.java
@@ -1,7 +1,9 @@
 package dev.zarr.zarrjava.v2;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.ObjectWriter;
 import dev.zarr.zarrjava.ZarrException;
+import dev.zarr.zarrjava.core.Attributes;
 import dev.zarr.zarrjava.store.FilesystemStore;
 import dev.zarr.zarrjava.store.StoreHandle;
 import dev.zarr.zarrjava.utils.Utils;
@@ -47,13 +49,19 @@ protected Array(StoreHandle storeHandle, ArrayMetadata arrayMetadata) throws IOE
    * @throws ZarrException throws ZarrException if the Zarr array cannot be opened
    */
   public static Array open(StoreHandle storeHandle) throws IOException, ZarrException {
+    ObjectMapper mapper = makeObjectMapper();
+    ArrayMetadata metadata = mapper.readValue(
+        Utils.toArray(storeHandle.resolve(ZARRAY).readNonNull()),
+        ArrayMetadata.class
+    );
+    if (storeHandle.resolve(ZATTRS).exists())
+      metadata.attributes = mapper.readValue(
+          Utils.toArray(storeHandle.resolve(ZATTRS).readNonNull()),
+          Attributes.class
+      );
     return new Array(
         storeHandle,
-        makeObjectMapper()
-            .readValue(
-                Utils.toArray(storeHandle.resolve(ZARRAY).readNonNull()),
-                ArrayMetadata.class
-            )
+        metadata
     );
   }
 
@@ -144,6 +152,12 @@ public static Array create(StoreHandle storeHandle, ArrayMetadata arrayMetadata,
     }
     ObjectWriter objectWriter = makeObjectWriter();
     ByteBuffer metadataBytes = ByteBuffer.wrap(objectWriter.writeValueAsBytes(arrayMetadata));
+    if (arrayMetadata.attributes != null) {
+      StoreHandle attrsHandle = storeHandle.resolve(ZATTRS);
+      ByteBuffer attrsBytes = ByteBuffer.wrap(
+          objectWriter.writeValueAsBytes(arrayMetadata.attributes));
+      attrsHandle.set(attrsBytes);
+    }
     metadataHandle.set(metadataBytes);
     return new Array(storeHandle, arrayMetadata);
   }
@@ -165,6 +179,61 @@ public static ArrayMetadataBuilder metadataBuilder(ArrayMetadata existingMetadat
     return ArrayMetadataBuilder.fromArrayMetadata(existingMetadata);
   }
 
+  private Array writeMetadata(ArrayMetadata newArrayMetadata) throws ZarrException, IOException {
+    return Array.create(storeHandle, newArrayMetadata, true);
+  }
+
+  /**
+   * Sets a new shape for the Zarr array. It only changes the metadata, no array data is modified or
+   * deleted. This method returns a new instance of the Zarr array class and the old instance
+   * becomes invalid.
+   *
+   * @param newShape the new shape of the Zarr array
+   * @throws ZarrException if the new metadata is invalid
+   * @throws IOException throws IOException if the new metadata cannot be serialized
+   */
+  public Array resize(long[] newShape) throws ZarrException, IOException {
+    if (newShape.length != metadata.ndim()) {
+      throw new IllegalArgumentException(
+          "'newShape' needs to have rank '" + metadata.ndim() + "'.");
+    }
+
+    ArrayMetadata newArrayMetadata = ArrayMetadataBuilder.fromArrayMetadata(metadata)
+        .withShape(newShape)
+        .build();
+    return writeMetadata(newArrayMetadata);
+  }
+
+  /**
+   * Sets the attributes of the Zarr array. It overwrites and removes any existing attributes. This
+   * method returns a new instance of the Zarr array class and the old instance becomes invalid.
+   *
+   * @param newAttributes the new attributes of the Zarr array
+   * @throws ZarrException throws ZarrException if the new metadata is invalid
+   * @throws IOException throws IOException if the new metadata cannot be serialized
+   */
+  public Array setAttributes(Attributes newAttributes) throws ZarrException, IOException {
+    ArrayMetadata newArrayMetadata =
+        ArrayMetadataBuilder.fromArrayMetadata(metadata, false)
+            .withAttributes(newAttributes)
+            .build();
+    return writeMetadata(newArrayMetadata);
+  }
+
+  /**
+   * Updates the attributes of the Zarr array. It provides a callback that gets the current
+   * attributes as input and needs to return the new set of attributes. The attributes in the
+   * callback may be mutated. This method overwrites and removes any existing attributes. This
+   * method returns a new instance of the Zarr array class and the old instance becomes invalid.
+   *
+   * @param attributeMapper the callback that is used to construct the new attributes
+   * @throws ZarrException throws ZarrException if the new metadata is invalid
+   * @throws IOException   throws IOException if the new metadata cannot be serialized
+   */
+  public Array updateAttributes(Function<Attributes, Attributes> attributeMapper) throws ZarrException, IOException {
+    return setAttributes(attributeMapper.apply(metadata.attributes));
+  }
+
   @Override
   public String toString() {
     return String.format("<v2.Array {%s} (%s) %s>", storeHandle,
diff --git a/src/main/java/dev/zarr/zarrjava/v2/ArrayMetadata.java b/src/main/java/dev/zarr/zarrjava/v2/ArrayMetadata.java
index dabd2855..b53eee3d 100644
--- a/src/main/java/dev/zarr/zarrjava/v2/ArrayMetadata.java
+++ b/src/main/java/dev/zarr/zarrjava/v2/ArrayMetadata.java
@@ -4,6 +4,7 @@
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import dev.zarr.zarrjava.ZarrException;
+import dev.zarr.zarrjava.core.Attributes;
 import dev.zarr.zarrjava.core.chunkkeyencoding.ChunkKeyEncoding;
 import dev.zarr.zarrjava.utils.MultiArrayUtils;
 import dev.zarr.zarrjava.core.chunkkeyencoding.Separator;
@@ -11,6 +12,7 @@
 import dev.zarr.zarrjava.v2.codec.Codec;
 import ucar.ma2.Array;
 
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
 
@@ -39,6 +41,10 @@ public class ArrayMetadata extends dev.zarr.zarrjava.core.ArrayMetadata {
   @Nullable
   public final Codec compressor;
 
+  @Nullable
+  @JsonIgnore
+  public Attributes attributes;
+
   @JsonIgnore
   public CoreArrayMetadata coreArrayMetadata;
 
@@ -54,6 +60,22 @@ public ArrayMetadata(
       @Nullable @JsonProperty(value = "filters", required = true) Codec[] filters,
       @Nullable @JsonProperty(value = "compressor", required = true) Codec compressor,
       @Nullable @JsonProperty(value = "dimension_separator") Separator dimensionSeparator
+      ) throws ZarrException {
+    this(zarrFormat, shape, chunks, dataType, fillValue, order, filters, compressor, dimensionSeparator, null);
+  }
+
+
+  public ArrayMetadata(
+      int zarrFormat,
+      long[] shape,
+      int[] chunks,
+      DataType dataType,
+      @Nullable Object fillValue,
+      Order order,
+      @Nullable Codec[] filters,
+      @Nullable Codec compressor,
+      @Nullable Separator dimensionSeparator,
+      @Nullable Attributes attributes
   ) throws ZarrException {
     super(shape, fillValue, dataType);
     if (zarrFormat != this.zarrFormat) {
@@ -78,6 +100,7 @@ public ArrayMetadata(
       }
     }
     this.compressor = compressor == null ? null : compressor.evolveFromCoreArrayMetadata(this.coreArrayMetadata);
+    this.attributes = attributes;
   }
 
 
@@ -87,8 +110,6 @@ public int[] chunkShape() {
     return chunks;
   }
 
-
-
   @Override
   public DataType dataType() {
     return dataType;
@@ -111,4 +132,14 @@ public ChunkKeyEncoding chunkKeyEncoding() {
   public Object parsedFillValue() {
     return parsedFillValue;
   }
+
+  @Override
+  public @Nonnull Attributes attributes() throws ZarrException {
+    if (attributes == null) {
+      throw new ZarrException("Array attributes have not been set.");
+    }
+    return attributes;
+  }
+
+
 }
diff --git a/src/main/java/dev/zarr/zarrjava/v2/ArrayMetadataBuilder.java b/src/main/java/dev/zarr/zarrjava/v2/ArrayMetadataBuilder.java
index ea29b165..7f27567f 100644
--- a/src/main/java/dev/zarr/zarrjava/v2/ArrayMetadataBuilder.java
+++ b/src/main/java/dev/zarr/zarrjava/v2/ArrayMetadataBuilder.java
@@ -2,6 +2,7 @@
 
 import com.scalableminds.bloscjava.Blosc;
 import dev.zarr.zarrjava.ZarrException;
+import dev.zarr.zarrjava.core.Attributes;
 import dev.zarr.zarrjava.core.chunkkeyencoding.Separator;
 import dev.zarr.zarrjava.v2.codec.Codec;
 import dev.zarr.zarrjava.v2.codec.core.BloscCodec;
@@ -16,12 +17,17 @@ public class ArrayMetadataBuilder {
   Object fillValue = null;
   Codec[] filters = null;
   Codec compressor = null;
+  Attributes attributes = new Attributes();
 
 
   protected ArrayMetadataBuilder() {
   }
 
   protected static ArrayMetadataBuilder fromArrayMetadata(ArrayMetadata arrayMetadata) {
+    return fromArrayMetadata(arrayMetadata, true);
+  }
+
+  protected static ArrayMetadataBuilder fromArrayMetadata(ArrayMetadata arrayMetadata, boolean withAttributes) {
     ArrayMetadataBuilder builder = new ArrayMetadataBuilder();
     builder.shape = arrayMetadata.shape;
     builder.chunks = arrayMetadata.chunks;
@@ -31,6 +37,9 @@ protected static ArrayMetadataBuilder fromArrayMetadata(ArrayMetadata arrayMetad
     builder.fillValue = arrayMetadata.parsedFillValue;
     builder.filters = arrayMetadata.filters;
     builder.compressor = arrayMetadata.compressor;
+    if (withAttributes) {
+      builder.attributes = arrayMetadata.attributes;
+    }
     return builder;
   }
 
@@ -119,6 +128,19 @@ public ArrayMetadataBuilder withZlibCompressor() {
     return withZlibCompressor(5);
   }
 
+  public ArrayMetadataBuilder putAttribute(String key, Object value) {
+    this.attributes.put(key, value);
+    return this;
+  }
+
+  public ArrayMetadataBuilder withAttributes(Attributes attributes) {
+    if (this.attributes == null) {
+      this.attributes = attributes;
+    } else {
+      this.attributes.putAll(attributes);
+    }
+    return this;
+  }
   public ArrayMetadata build() throws ZarrException {
     if (shape == null) {
       throw new IllegalStateException("Please call `withShape` first.");
@@ -138,7 +160,8 @@ public ArrayMetadata build() throws ZarrException {
         order,
         filters,
         compressor,
-        dimensionSeparator
+        dimensionSeparator,
+        attributes
     );
   }
 }
\ No newline at end of file
diff --git a/src/main/java/dev/zarr/zarrjava/v2/Group.java b/src/main/java/dev/zarr/zarrjava/v2/Group.java
index c8982e13..701e7871 100644
--- a/src/main/java/dev/zarr/zarrjava/v2/Group.java
+++ b/src/main/java/dev/zarr/zarrjava/v2/Group.java
@@ -1,7 +1,9 @@
 package dev.zarr.zarrjava.v2;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.ObjectWriter;
 import dev.zarr.zarrjava.ZarrException;
+import dev.zarr.zarrjava.core.Attributes;
 import dev.zarr.zarrjava.store.FilesystemStore;
 import dev.zarr.zarrjava.store.StoreHandle;
 import dev.zarr.zarrjava.utils.Utils;
@@ -25,10 +27,17 @@ protected Group(@Nonnull StoreHandle storeHandle, @Nonnull GroupMetadata groupMe
   }
 
   public static Group open(@Nonnull StoreHandle storeHandle) throws IOException {
-    StoreHandle metadataHandle = storeHandle.resolve(ZGROUP);
-    ByteBuffer metadataBytes = metadataHandle.readNonNull();
-    return new Group(storeHandle, makeObjectMapper()
-        .readValue(Utils.toArray(metadataBytes), GroupMetadata.class));
+    ObjectMapper mapper = makeObjectMapper();
+    GroupMetadata metadata = mapper.readValue(
+        Utils.toArray(storeHandle.resolve(ZGROUP).readNonNull()),
+        GroupMetadata.class
+    );
+    if (storeHandle.resolve(ZATTRS).exists())
+      metadata.attributes = mapper.readValue(
+          Utils.toArray(storeHandle.resolve(ZATTRS).readNonNull()),
+          dev.zarr.zarrjava.core.Attributes.class
+      );
+    return new Group(storeHandle, metadata);
   }
 
   public static Group open(Path path) throws IOException {
@@ -45,6 +54,12 @@ public static Group create(
     ObjectWriter objectWriter = makeObjectWriter();
     ByteBuffer metadataBytes = ByteBuffer.wrap(objectWriter.writeValueAsBytes(groupMetadata));
     storeHandle.resolve(ZGROUP).set(metadataBytes);
+    if (groupMetadata.attributes != null) {
+      StoreHandle attrsHandle = storeHandle.resolve(ZATTRS);
+      ByteBuffer attrsBytes = ByteBuffer.wrap(
+          objectWriter.writeValueAsBytes(groupMetadata.attributes));
+      attrsHandle.set(attrsBytes);
+    }
     return new Group(storeHandle, groupMetadata);
   }
 
@@ -52,14 +67,26 @@ public static Group create(@Nonnull StoreHandle storeHandle) throws IOException,
     return create(storeHandle, new GroupMetadata());
   }
 
+  public static Group create(@Nonnull StoreHandle storeHandle, Attributes attributes) throws IOException, ZarrException {
+    return create(storeHandle, new GroupMetadata(attributes));
+  }
+
   public static Group create(Path path) throws IOException, ZarrException {
     return create(new StoreHandle(new FilesystemStore(path)));
   }
 
+  public static Group create(Path path, Attributes attributes) throws IOException, ZarrException {
+    return create(new StoreHandle(new FilesystemStore(path)), attributes);
+  }
+
   public static Group create(String path) throws IOException, ZarrException {
     return create(Paths.get(path));
   }
 
+  public static Group create(String path, Attributes attributes) throws IOException, ZarrException {
+    return create(Paths.get(path), attributes);
+  }
+
   @Nullable
   public Node get(String key) throws ZarrException {
     StoreHandle keyHandle = storeHandle.resolve(key);
@@ -88,4 +115,9 @@ public Array createArray(String key, Function<ArrayMetadataBuilder, ArrayMetadat
   public String toString() {
     return String.format("<v2.Group {%s}>", storeHandle);
   }
+
+  @Override
+  public GroupMetadata metadata() {
+    return metadata;
+  }
 }
diff --git a/src/main/java/dev/zarr/zarrjava/v2/GroupMetadata.java b/src/main/java/dev/zarr/zarrjava/v2/GroupMetadata.java
index e32f1065..e0e6c00e 100644
--- a/src/main/java/dev/zarr/zarrjava/v2/GroupMetadata.java
+++ b/src/main/java/dev/zarr/zarrjava/v2/GroupMetadata.java
@@ -1,8 +1,13 @@
 package dev.zarr.zarrjava.v2;
 
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
 import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import dev.zarr.zarrjava.ZarrException;
+import dev.zarr.zarrjava.core.Attributes;
 
 public final class GroupMetadata extends dev.zarr.zarrjava.core.GroupMetadata {
 
@@ -10,18 +15,35 @@ public final class GroupMetadata extends dev.zarr.zarrjava.core.GroupMetadata {
   @JsonProperty("zarr_format")
   public final int zarrFormat = ZARR_FORMAT;
 
+  @Nullable
+  @JsonIgnore
+  public Attributes attributes;
+
   @JsonCreator(mode = JsonCreator.Mode.PROPERTIES)
   public GroupMetadata(
-      @JsonProperty(value = "zarr_format", required = true) int zarrFormat
+      @JsonProperty(value = "zarr_format", required = true) int zarrFormat,
+      @JsonProperty(value = "attributes", required = false) @Nullable Attributes attributes
   ) throws ZarrException {
     if (zarrFormat != this.zarrFormat) {
       throw new ZarrException(
           "Expected zarr format '" + this.zarrFormat + "', got '" + zarrFormat + "'.");
     }
+    this.attributes = attributes;
   }
 
   public GroupMetadata() throws ZarrException {
-    this(ZARR_FORMAT);
+    this(ZARR_FORMAT, null);
+  }
+
+  public GroupMetadata(Attributes attributes) throws ZarrException {
+    this(ZARR_FORMAT, attributes);
   }
 
+  @Override
+  public @Nonnull Attributes attributes() throws ZarrException {
+    if (attributes == null) {
+      throw new ZarrException("Group attributes have not been set.");
+    }
+    return attributes;
+  }
 }
diff --git a/src/main/java/dev/zarr/zarrjava/v3/Array.java b/src/main/java/dev/zarr/zarrjava/v3/Array.java
index 19c82fbf..1536893c 100644
--- a/src/main/java/dev/zarr/zarrjava/v3/Array.java
+++ b/src/main/java/dev/zarr/zarrjava/v3/Array.java
@@ -2,6 +2,7 @@
 
 import com.fasterxml.jackson.databind.ObjectWriter;
 import dev.zarr.zarrjava.ZarrException;
+import dev.zarr.zarrjava.core.Attributes;
 import dev.zarr.zarrjava.store.FilesystemStore;
 import dev.zarr.zarrjava.store.StoreHandle;
 import dev.zarr.zarrjava.utils.Utils;
@@ -11,8 +12,6 @@
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.Arrays;
-import java.util.HashMap;
-import java.util.Map;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 import javax.annotation.Nonnull;
@@ -183,11 +182,7 @@ public static ArrayMetadataBuilder metadataBuilder(ArrayMetadata existingMetadat
   }
 
   private Array writeMetadata(ArrayMetadata newArrayMetadata) throws ZarrException, IOException {
-    ObjectWriter objectWriter = makeObjectWriter();
-    ByteBuffer metadataBytes = ByteBuffer.wrap(objectWriter.writeValueAsBytes(newArrayMetadata));
-    storeHandle.resolve(ZARR_JSON)
-        .set(metadataBytes);
-    return new Array(storeHandle, newArrayMetadata);
+    return Array.create(storeHandle, newArrayMetadata, true);
   }
 
   /**
@@ -219,9 +214,9 @@ public Array resize(long[] newShape) throws ZarrException, IOException {
    * @throws ZarrException throws ZarrException if the new metadata is invalid
    * @throws IOException throws IOException if the new metadata cannot be serialized
    */
-  public Array setAttributes(Map<String, Object> newAttributes) throws ZarrException, IOException {
+  public Array setAttributes(Attributes newAttributes) throws ZarrException, IOException {
     ArrayMetadata newArrayMetadata =
-        ArrayMetadataBuilder.fromArrayMetadata(metadata)
+        ArrayMetadataBuilder.fromArrayMetadata(metadata, false)
             .withAttributes(newAttributes)
             .build();
     return writeMetadata(newArrayMetadata);
@@ -235,12 +230,10 @@ public Array setAttributes(Map<String, Object> newAttributes) throws ZarrExcepti
    *
    * @param attributeMapper the callback that is used to construct the new attributes
    * @throws ZarrException throws ZarrException if the new metadata is invalid
-   * @throws IOException throws IOException if the new metadata cannot be serialized
+   * @throws IOException   throws IOException if the new metadata cannot be serialized
    */
-  public Array updateAttributes(Function<Map<String, Object>, Map<String, Object>> attributeMapper)
-      throws ZarrException, IOException {
-    return setAttributes(attributeMapper.apply(new HashMap<String, Object>(metadata.attributes) {
-    }));
+  public Array updateAttributes(Function<Attributes, Attributes> attributeMapper) throws ZarrException, IOException {
+    return setAttributes(attributeMapper.apply(metadata.attributes));
   }
 
   @Override
diff --git a/src/main/java/dev/zarr/zarrjava/v3/ArrayMetadata.java b/src/main/java/dev/zarr/zarrjava/v3/ArrayMetadata.java
index 36253482..eb500326 100644
--- a/src/main/java/dev/zarr/zarrjava/v3/ArrayMetadata.java
+++ b/src/main/java/dev/zarr/zarrjava/v3/ArrayMetadata.java
@@ -4,6 +4,7 @@
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import dev.zarr.zarrjava.ZarrException;
+import dev.zarr.zarrjava.core.Attributes;
 import dev.zarr.zarrjava.v3.chunkgrid.ChunkGrid;
 import dev.zarr.zarrjava.v3.chunkgrid.RegularChunkGrid;
 import dev.zarr.zarrjava.v3.chunkkeyencoding.ChunkKeyEncoding;
@@ -39,7 +40,7 @@ public final class ArrayMetadata extends dev.zarr.zarrjava.core.ArrayMetadata {
   public final Codec[] codecs;
   @Nullable
   @JsonProperty("attributes")
-  public final Map<String, Object> attributes;
+  public final Attributes attributes;
   @Nullable
   @JsonProperty("dimension_names")
   public final String[] dimensionNames;
@@ -55,7 +56,7 @@ public ArrayMetadata(
       Object fillValue,
       @Nonnull Codec[] codecs,
       @Nullable String[] dimensionNames,
-      @Nullable Map<String, Object> attributes,
+      @Nullable Attributes attributes,
       @Nullable Map<String, Object>[] storageTransformers
   ) throws ZarrException {
     this(ZARR_FORMAT, NODE_TYPE, shape, dataType, chunkGrid, chunkKeyEncoding, fillValue, codecs,
@@ -75,7 +76,7 @@ public ArrayMetadata(
       @JsonProperty(value = "fill_value", required = true) Object fillValue,
       @Nonnull @JsonProperty(value = "codecs") Codec[] codecs,
       @Nullable @JsonProperty(value = "dimension_names") String[] dimensionNames,
-      @Nullable @JsonProperty(value = "attributes") Map<String, Object> attributes,
+      @Nullable @JsonProperty(value = "attributes") Attributes attributes,
       @Nullable @JsonProperty(value = "storage_transformers") Map<String, Object>[] storageTransformers
   ) throws ZarrException {
     super(shape, fillValue, dataType);
@@ -143,6 +144,15 @@ public Object parsedFillValue() {
     return parsedFillValue;
   }
 
+  @Nonnull
+  @Override
+  public Attributes attributes() throws ZarrException {
+    if (attributes == null) {
+      throw new ZarrException("Array attributes have not been set.");
+    }
+    return attributes;
+  }
+
   public static Optional<Codec> getShardingIndexedCodec(Codec[] codecs) {
     return Arrays.stream(codecs).filter(codec -> codec instanceof ShardingIndexedCodec).findFirst();
   }
diff --git a/src/main/java/dev/zarr/zarrjava/v3/ArrayMetadataBuilder.java b/src/main/java/dev/zarr/zarrjava/v3/ArrayMetadataBuilder.java
index 417d8ede..1da2015f 100644
--- a/src/main/java/dev/zarr/zarrjava/v3/ArrayMetadataBuilder.java
+++ b/src/main/java/dev/zarr/zarrjava/v3/ArrayMetadataBuilder.java
@@ -1,6 +1,7 @@
 package dev.zarr.zarrjava.v3;
 
 import dev.zarr.zarrjava.ZarrException;
+import dev.zarr.zarrjava.core.Attributes;
 import dev.zarr.zarrjava.v3.chunkgrid.ChunkGrid;
 import dev.zarr.zarrjava.v3.chunkgrid.RegularChunkGrid;
 import dev.zarr.zarrjava.v3.chunkkeyencoding.ChunkKeyEncoding;
@@ -26,7 +27,7 @@ public class ArrayMetadataBuilder {
 
   Object fillValue = 0;
   Codec[] codecs = new Codec[]{new BytesCodec(Endian.LITTLE)};
-  Map<String, Object> attributes = new HashMap<>();
+  Attributes attributes = new Attributes();
   Map<String, Object>[] storageTransformers = new HashMap[]{};
   String[] dimensionNames = null;
 
@@ -34,6 +35,10 @@ protected ArrayMetadataBuilder() {
   }
 
   protected static ArrayMetadataBuilder fromArrayMetadata(ArrayMetadata arrayMetadata) {
+    return fromArrayMetadata(arrayMetadata, true);
+  }
+
+  protected static ArrayMetadataBuilder fromArrayMetadata(ArrayMetadata arrayMetadata, boolean withAttributes) {
     ArrayMetadataBuilder builder = new ArrayMetadataBuilder();
     builder.shape = arrayMetadata.shape;
     builder.dataType = arrayMetadata.dataType;
@@ -41,9 +46,11 @@ protected static ArrayMetadataBuilder fromArrayMetadata(ArrayMetadata arrayMetad
     builder.chunkKeyEncoding = arrayMetadata.chunkKeyEncoding;
     builder.fillValue = arrayMetadata.parsedFillValue;
     builder.codecs = arrayMetadata.codecs;
-    builder.attributes = arrayMetadata.attributes;
     builder.dimensionNames = arrayMetadata.dimensionNames;
     builder.storageTransformers = arrayMetadata.storageTransformers;
+    if (withAttributes) {
+      builder.attributes = arrayMetadata.attributes;
+    }
     return builder;
   }
 
@@ -133,8 +140,12 @@ public ArrayMetadataBuilder putAttribute(String key, Object value) {
     return this;
   }
 
-  public ArrayMetadataBuilder withAttributes(Map<String, Object> attributes) {
-    this.attributes = attributes;
+  public ArrayMetadataBuilder withAttributes(Attributes attributes) {
+    if (this.attributes == null) {
+      this.attributes = attributes;
+    } else {
+      this.attributes.putAll(attributes);
+    }
     return this;
   }
 
diff --git a/src/main/java/dev/zarr/zarrjava/v3/Group.java b/src/main/java/dev/zarr/zarrjava/v3/Group.java
index 7b025975..62a36c8e 100644
--- a/src/main/java/dev/zarr/zarrjava/v3/Group.java
+++ b/src/main/java/dev/zarr/zarrjava/v3/Group.java
@@ -2,6 +2,7 @@
 
 import com.fasterxml.jackson.databind.ObjectWriter;
 import dev.zarr.zarrjava.ZarrException;
+import dev.zarr.zarrjava.core.Attributes;
 import dev.zarr.zarrjava.store.FilesystemStore;
 import dev.zarr.zarrjava.store.StoreHandle;
 import dev.zarr.zarrjava.utils.Utils;
@@ -9,7 +10,6 @@
 import java.nio.ByteBuffer;
 import java.nio.file.Path;
 import java.nio.file.Paths;
-import java.util.Map;
 import java.util.function.Function;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
@@ -54,9 +54,9 @@ public static Group create(
 
   public static Group create(
       @Nonnull StoreHandle storeHandle,
-      @Nonnull Map<String, Object> attributes
+      @Nonnull Attributes attributes
   ) throws IOException, ZarrException {
-    return new Group(storeHandle, new GroupMetadata(attributes));
+    return create(storeHandle, new GroupMetadata(attributes));
   }
 
   public static Group create(@Nonnull StoreHandle storeHandle) throws IOException, ZarrException {
@@ -94,7 +94,7 @@ public Group createGroup(String key, GroupMetadata groupMetadata)
     return Group.create(storeHandle.resolve(key), groupMetadata);
   }
 
-  public Group createGroup(String key, Map<String, Object> attributes)
+  public Group createGroup(String key, Attributes attributes)
       throws IOException, ZarrException {
     return Group.create(storeHandle.resolve(key), new GroupMetadata(attributes));
   }
@@ -122,12 +122,12 @@ private Group writeMetadata(GroupMetadata newGroupMetadata) throws IOException {
     return new Group(storeHandle, newGroupMetadata);
   }
 
-  public Group setAttributes(Map<String, Object> newAttributes) throws ZarrException, IOException {
+  public Group setAttributes(Attributes newAttributes) throws ZarrException, IOException {
     GroupMetadata newGroupMetadata = new GroupMetadata(newAttributes);
     return writeMetadata(newGroupMetadata);
   }
 
-  public Group updateAttributes(Function<Map<String, Object>, Map<String, Object>> attributeMapper)
+  public Group updateAttributes(Function<Attributes, Attributes> attributeMapper)
       throws ZarrException, IOException {
     return setAttributes(attributeMapper.apply(metadata.attributes));
   }
@@ -136,4 +136,9 @@ public Group updateAttributes(Function<Map<String, Object>, Map<String, Object>>
   public String toString() {
     return String.format("<v3.Group {%s}>", storeHandle);
   }
+
+  @Override
+  public GroupMetadata metadata() {
+    return metadata;
+  }
 }
diff --git a/src/main/java/dev/zarr/zarrjava/v3/GroupMetadata.java b/src/main/java/dev/zarr/zarrjava/v3/GroupMetadata.java
index df32c046..e7618736 100644
--- a/src/main/java/dev/zarr/zarrjava/v3/GroupMetadata.java
+++ b/src/main/java/dev/zarr/zarrjava/v3/GroupMetadata.java
@@ -1,10 +1,12 @@
 package dev.zarr.zarrjava.v3;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import dev.zarr.zarrjava.ZarrException;
-import java.util.HashMap;
-import java.util.Map;
+import dev.zarr.zarrjava.core.Attributes;
+
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
 public final class GroupMetadata extends dev.zarr.zarrjava.core.GroupMetadata {
@@ -15,11 +17,13 @@ public final class GroupMetadata extends dev.zarr.zarrjava.core.GroupMetadata {
   public final int zarrFormat = ZARR_FORMAT;
   @JsonProperty("node_type")
   public final String nodeType = "group";
+  @JsonProperty("consolidated_metadata")
+  public final String consolidatedMetadata = null;
 
   @Nullable
-  public final Map<String, Object> attributes;
+  public final Attributes attributes;
 
-  public GroupMetadata(@Nullable Map<String, Object> attributes) throws ZarrException {
+  public GroupMetadata(@Nullable Attributes attributes) throws ZarrException {
     this(ZARR_FORMAT, NODE_TYPE, attributes);
   }
 
@@ -27,7 +31,7 @@ public GroupMetadata(@Nullable Map<String, Object> attributes) throws ZarrExcept
   public GroupMetadata(
       @JsonProperty(value = "zarr_format", required = true) int zarrFormat,
       @JsonProperty(value = "node_type", required = true) String nodeType,
-      @Nullable @JsonProperty(value = "attributes") Map<String, Object> attributes
+      @Nullable @JsonProperty(value = "attributes") Attributes attributes
   ) throws ZarrException {
     if (zarrFormat != this.zarrFormat) {
       throw new ZarrException(
@@ -41,6 +45,14 @@ public GroupMetadata(
   }
 
   public static GroupMetadata defaultValue() throws ZarrException {
-    return new GroupMetadata(ZARR_FORMAT, NODE_TYPE, new HashMap<>());
+    return new GroupMetadata(ZARR_FORMAT, NODE_TYPE, new Attributes());
+  }
+
+  @Override
+  public @Nonnull Attributes attributes() throws ZarrException {
+  if (attributes == null) {
+      throw new ZarrException("Group attributes have not been set.");
+    }
+    return attributes;
   }
 }
diff --git a/src/test/java/dev/zarr/zarrjava/ZarrPythonTests.java b/src/test/java/dev/zarr/zarrjava/ZarrPythonTests.java
index 1f2899f3..1a6faade 100644
--- a/src/test/java/dev/zarr/zarrjava/ZarrPythonTests.java
+++ b/src/test/java/dev/zarr/zarrjava/ZarrPythonTests.java
@@ -2,6 +2,7 @@
 
 import com.github.luben.zstd.Zstd;
 import com.github.luben.zstd.ZstdCompressCtx;
+import dev.zarr.zarrjava.core.Attributes;
 import dev.zarr.zarrjava.store.FilesystemStore;
 import dev.zarr.zarrjava.store.StoreHandle;
 import dev.zarr.zarrjava.v2.Group;
@@ -209,7 +210,7 @@ public void testReadV3(String codec, String codecParam, DataType dataType) throw
     @ParameterizedTest
     @MethodSource("compressorAndDataTypeProviderV3")
     public void testWriteV3(String codec, String codecParam, DataType dataType) throws Exception {
-        Map<String, Object> attributes = new HashMap<>();
+        Attributes attributes = new Attributes();
         attributes.put("test_key", "test_value");
         StoreHandle storeHandle = new FilesystemStore(TESTOUTPUT).resolve("testWriteV3", codec, codecParam, dataType.name());
 
@@ -314,7 +315,7 @@ public void testReadV2(String compressor, String compressorParam, dev.zarr.zarrj
         Assertions.assertArrayEquals(new int[]{16, 16, 16}, result.getShape());
         Assertions.assertEquals(dt, array.metadata().dataType);
         Assertions.assertArrayEquals(new int[]{2, 4, 8}, array.metadata().chunkShape());
-//        Assertions.assertEquals(42, array.metadata().attributes.get("answer"));
+        Assertions.assertEquals(42, array.metadata().attributes().get("answer"));
 
         assertIsTestdata(result, dt);
     }
@@ -323,15 +324,15 @@ public void testReadV2(String compressor, String compressorParam, dev.zarr.zarrj
     @ParameterizedTest
     @MethodSource("compressorAndDataTypeProviderV2")
     public void testWriteV2(String compressor, String compressorParam, dev.zarr.zarrjava.v2.DataType dt) throws Exception {
-//        Map<String, Object> attributes = new HashMap<>();
-//        attributes.put("test_key", "test_value");
+        Attributes attributes = new Attributes();
+        attributes.put("test_key", "test_value");
         StoreHandle storeHandle = new FilesystemStore(TESTOUTPUT).resolve("testCodecsWriteV2", compressor, compressorParam, dt.name());
 
         dev.zarr.zarrjava.v2.ArrayMetadataBuilder builder = dev.zarr.zarrjava.v2.Array.metadataBuilder()
             .withShape(16, 16, 16)
             .withDataType(dt)
             .withChunks(2, 4, 8)
-//            .withAttributes(attributes)
+            .withAttributes(attributes)
             .withFillValue(0);
 
         switch (compressor) {
@@ -358,7 +359,7 @@ public void testWriteV2(String compressor, String compressorParam, dev.zarr.zarr
         Assertions.assertArrayEquals(new int[]{16, 16, 16}, result.getShape());
         Assertions.assertEquals(dt, readArray.metadata().dataType);
         Assertions.assertArrayEquals(new int[]{2, 4, 8}, readArray.metadata().chunkShape());
-//        Assertions.assertEquals("test_value", readArray.metadata.attributes.get("test_key"));
+        Assertions.assertEquals("test_value", readArray.metadata().attributes().get("test_key"));
         assertIsTestdata(result, dt);
 
         //read in zarr_python
@@ -401,9 +402,9 @@ public void testZstdLibrary(int clevel, boolean checksumFlag) throws IOException
 
     @Test
     public void testGroupReadWriteV2() throws Exception {
-        StoreHandle storeHandle = new FilesystemStore(TESTOUTPUT).resolve("group_write");
-        StoreHandle storeHandle2 = new FilesystemStore(TESTOUTPUT).resolve("group_read");
-        Group group = Group.create(storeHandle);
+        StoreHandle storeHandle = new FilesystemStore(TESTOUTPUT).resolve("testGroupReadWriteV2", "write");
+        StoreHandle storeHandle2 = new FilesystemStore(TESTOUTPUT).resolve("testGroupReadWriteV2", "read");
+        Group group = Group.create(storeHandle, new Attributes(b -> b.set("attr", "value")));
         dev.zarr.zarrjava.v2.DataType dataType = dev.zarr.zarrjava.v2.DataType.INT32;
         dev.zarr.zarrjava.v2.Array array = group.createGroup("group").createArray("array", arrayMetadataBuilder -> arrayMetadataBuilder
                 .withShape(16, 16, 16)
@@ -413,9 +414,10 @@ public void testGroupReadWriteV2() throws Exception {
 
         array.write(testdata(dataType));
 
-        run_python_script("zarr_python_group_v2.py", storeHandle.toPath().toString(), storeHandle2.toPath().toString());
+        run_python_script("zarr_python_group.py", storeHandle.toPath().toString(), storeHandle2.toPath().toString(), "" + 2);
 
         Group group2 = Group.open(storeHandle2);
+        Assertions.assertEquals("value", group2.metadata().attributes().get("attr"));
         Group subgroup = (Group) group2.get("group2");
         Assertions.assertNotNull(subgroup);
         dev.zarr.zarrjava.v2.Array array2 = (dev.zarr.zarrjava.v2.Array) subgroup.get("array2");
@@ -424,4 +426,31 @@ public void testGroupReadWriteV2() throws Exception {
         Assertions.assertArrayEquals(new int[]{16, 16, 16}, result.getShape());
         assertIsTestdata(result, dataType);
     }
+
+    @Test
+    public void testGroupReadWriteV3() throws Exception {
+        StoreHandle storeHandle = new FilesystemStore(TESTOUTPUT).resolve("testGroupReadWriteV3", "write");
+        StoreHandle storeHandle2 = new FilesystemStore(TESTOUTPUT).resolve("testGroupReadWriteV3", "read");
+        dev.zarr.zarrjava.v3.Group group = dev.zarr.zarrjava.v3.Group.create(storeHandle, new Attributes(b -> b.set("attr", "value")));
+        dev.zarr.zarrjava.v3.DataType dataType = DataType.INT32;
+        dev.zarr.zarrjava.v3.Array array = group.createGroup("group").createArray("array", arrayMetadataBuilder -> arrayMetadataBuilder
+                .withShape(16, 16, 16)
+                .withDataType(dataType)
+                .withChunkShape(2, 4, 8)
+            );
+
+        array.write(testdata(dataType));
+
+        run_python_script("zarr_python_group.py", storeHandle.toPath().toString(), storeHandle2.toPath().toString(), "" + 3);
+
+        dev.zarr.zarrjava.v3.Group group2 = dev.zarr.zarrjava.v3.Group.open(storeHandle2);
+        Assertions.assertEquals("value", group2.metadata().attributes().get("attr"));
+        dev.zarr.zarrjava.v3.Group subgroup = (dev.zarr.zarrjava.v3.Group) group2.get("group2");
+        Assertions.assertNotNull(subgroup);
+        dev.zarr.zarrjava.v3.Array array2 = (dev.zarr.zarrjava.v3.Array) subgroup.get("array2");
+        Assertions.assertNotNull(array2);
+        ucar.ma2.Array result = array2.read();
+        Assertions.assertArrayEquals(new int[]{16, 16, 16}, result.getShape());
+        assertIsTestdata(result, dataType);
+    }
 }
diff --git a/src/test/java/dev/zarr/zarrjava/ZarrTest.java b/src/test/java/dev/zarr/zarrjava/ZarrTest.java
index b40d516d..8a6309d2 100644
--- a/src/test/java/dev/zarr/zarrjava/ZarrTest.java
+++ b/src/test/java/dev/zarr/zarrjava/ZarrTest.java
@@ -1,13 +1,16 @@
 package dev.zarr.zarrjava;
 
+import dev.zarr.zarrjava.core.Attributes;
+import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeAll;
 
-import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.ArrayList;
 import java.util.Comparator;
+import java.util.List;
 import java.util.stream.Stream;
 
 public class ZarrTest {
@@ -30,4 +33,83 @@ public static void clearTestoutputFolder() throws IOException {
         }
         Files.createDirectory(TESTOUTPUT);
     }
+
+    protected void assertListEquals(List<Object> a, List<Object> b) {
+        Assertions.assertEquals(a.size(), b.size());
+        for (int i = 0; i < a.size(); i++) {
+            Object aval = a.get(i);
+            Object bval = b.get(i);
+            if (aval instanceof List && bval instanceof List) {
+                assertListEquals((List<Object>) aval, (List<Object>) bval);
+            } else {
+                Assertions.assertEquals(aval, bval);
+            }
+        }
+    }
+
+    protected Attributes defaultTestAttributes() {
+        return new Attributes() {{
+            put("string", "stringvalue");
+            put("int", 42);
+            put("float", 0.5f);
+            put("double", 3.14);
+            put("boolean", true);
+            put("list", new ArrayList<Object>() {
+                {
+                    add(1);
+                    add(2.0d);
+                    add("string");
+                }
+            });
+            put("int_array", new int[]{1, 2, 3});
+            put("long_array", new long[]{1, 2, 3});
+            put("double_array", new double[]{1.0, 2.0, 3.0});
+            put("float_array", new float[]{1.0f, 2.0f, 3.0f});
+            put("boolean_array", new boolean[]{true, false, true});
+            put("nested", new Attributes() {{
+                put("element", "value");
+            }});
+            put("array_of_attributes", new Attributes[]{
+                new Attributes() {{
+                    put("a", 1);
+                }},
+                new Attributes() {{
+                    put("b", 2);
+                }}
+            });
+        }};
+    }
+
+    protected void assertContainsTestAttributes(Attributes attributes) throws ZarrException {
+        Assertions.assertEquals("stringvalue", attributes.getString("string"));
+        Assertions.assertEquals(42, attributes.getInt("int"));
+        Assertions.assertEquals(0.5, attributes.getFloat("float"));
+        Assertions.assertEquals(3.14, attributes.getDouble("double"));
+        Assertions.assertTrue(attributes.getBoolean("boolean"));
+        assertListEquals(new ArrayList<Object>() {
+            {
+                add(1);
+                add(2.0d);
+                add("string");
+            }
+        }, attributes.getList("list"));
+        Assertions.assertArrayEquals(new int[]{1, 2, 3}, attributes.getIntArray("int_array"));
+        Assertions.assertArrayEquals(new long[]{1, 2, 3}, attributes.getLongArray("long_array"));
+        Assertions.assertArrayEquals(new double[]{1, 2, 3}, attributes.getDoubleArray("double_array"));
+        Assertions.assertArrayEquals(new float[]{1, 2, 3}, attributes.getFloatArray("float_array"));
+        Assertions.assertArrayEquals(new boolean[]{true, false, true}, attributes.getBooleanArray("boolean_array"));
+        Assertions.assertEquals("value", attributes.getAttributes("nested").getString("element"));
+        Assertions.assertArrayEquals(
+            new Attributes[]{
+                new Attributes() {{
+                    put("a", 1);
+                }},
+                new Attributes() {{
+                    put("b", 2);
+                }}
+            },
+            attributes.getArray("array_of_attributes", Attributes.class)
+        );
+    }
+
 }
diff --git a/src/test/java/dev/zarr/zarrjava/ZarrV2Test.java b/src/test/java/dev/zarr/zarrjava/ZarrV2Test.java
index eb79cc83..f783646d 100644
--- a/src/test/java/dev/zarr/zarrjava/ZarrV2Test.java
+++ b/src/test/java/dev/zarr/zarrjava/ZarrV2Test.java
@@ -1,5 +1,6 @@
 package dev.zarr.zarrjava;
 
+import dev.zarr.zarrjava.core.Attributes;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import dev.zarr.zarrjava.store.FilesystemStore;
@@ -18,6 +19,7 @@
 import java.nio.file.NoSuchFileException;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.Arrays;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
@@ -45,8 +47,6 @@ public void testCreateBlosc(String cname, String shuffle, int clevel) throws IOE
         Assertions.assertEquals(0, outArray.getByte(0));
     }
 
-
-
     @ParameterizedTest
     @CsvSource({
         "BOOL", "FLOAT64"
@@ -55,7 +55,7 @@ public void testReadBloscDetectTypesize(DataType dt) throws IOException, ZarrExc
         String arrayname = dt == DataType.BOOL ? "bool" : "double";
         StoreHandle storeHandle = new FilesystemStore(TESTDATA).resolve("v2_sample", arrayname);
         Array array = Array.open(storeHandle);
-        ucar.ma2.Array output = array.read(new long[]{0, 0, 0}, new int[]{3, 4, 5});
+        array.read(new long[]{0, 0, 0}, new int[]{3, 4, 5});
         Assertions.assertEquals(dt, array.metadata().dataType);
     }
 
@@ -259,6 +259,111 @@ public void testCreateGroup() throws ZarrException, IOException {
 
         Group.create(storeHandleString);
         Assertions.assertTrue(Files.exists(Paths.get(storeHandleString).resolve(".zgroup")));
+
+        Group.create(storeHandleString, new Attributes(b -> b.set("some", "value")));
+        Assertions.assertTrue(Files.exists(Paths.get(storeHandleString).resolve(".zgroup")));
+        Assertions.assertTrue(Files.exists(Paths.get(storeHandleString).resolve(".zattrs")));
+    }
+
+    @Test
+    public void testAttributes() throws IOException, ZarrException {
+        StoreHandle storeHandle = new FilesystemStore(TESTOUTPUT).resolve("testAttributesV2");
+
+        ArrayMetadata arrayMetadata = Array.metadataBuilder()
+            .withShape(10, 10)
+            .withDataType(DataType.UINT8)
+            .withChunks(5, 5)
+            .putAttribute("specific", "attribute")
+            .withAttributes(defaultTestAttributes())
+            .withAttributes(new Attributes() {{
+                put("another", "attribute");
+            }})
+            .build();
+
+        Array array = Array.create(storeHandle, arrayMetadata);
+        assertContainsTestAttributes(array.metadata().attributes());
+        Assertions.assertEquals("attribute", array.metadata().attributes().getString("specific"));
+        Assertions.assertEquals("attribute", array.metadata().attributes().getString("another"));
+
+        Array arrayOpened = Array.open(storeHandle);
+        assertContainsTestAttributes(array.metadata().attributes());
+        Assertions.assertEquals("attribute", arrayOpened.metadata().attributes().getString("another"));
+        Assertions.assertEquals("attribute", arrayOpened.metadata().attributes().getString("specific"));
+    }
+
+    @Test
+    public void testSetAndUpdateAttributes() throws IOException, ZarrException {
+        StoreHandle storeHandle = new FilesystemStore(TESTOUTPUT).resolve("testSetAttributesV2");
+
+        ArrayMetadata arrayMetadata = Array.metadataBuilder()
+            .withShape(10, 10)
+            .withDataType(DataType.UINT8)
+            .withChunks(5, 5)
+            .withAttributes(new Attributes(b -> b.set("some", "value")))
+            .build();
+
+        Array array = Array.create(storeHandle, arrayMetadata);
+        Assertions.assertEquals("value", array.metadata().attributes().getString("some"));
+        array.setAttributes(defaultTestAttributes());
+        array = Array.open(storeHandle);
+        assertContainsTestAttributes(array.metadata().attributes());
+        Assertions.assertNull(array.metadata().attributes().get("some"));
+
+        // add attribute
+        array = array.updateAttributes(b -> b.set("new_attribute", "new_value"));
+        Assertions.assertEquals("new_value", array.metadata().attributes().getString("new_attribute"));
+        array = Array.open(storeHandle);
+        Assertions.assertEquals("new_value", array.metadata().attributes().getString("new_attribute"));
+
+        // delete attribute
+        array = array.updateAttributes(b -> b.delete("new_value"));
+        Assertions.assertNull(array.metadata().attributes().get("new_value"));
+        array = Array.open(storeHandle);
+        Assertions.assertNull(array.metadata().attributes().get("new_value"));
+
+        assertContainsTestAttributes(array.metadata().attributes());
+    }
+
+    @Test
+    public void testResizeArray() throws IOException, ZarrException {
+        int[] testData = new int[10 * 10];
+        Arrays.setAll(testData, p -> p);
+
+        StoreHandle storeHandle = new FilesystemStore(TESTOUTPUT).resolve("testResizeArrayV2");
+        ArrayMetadata arrayMetadata = Array.metadataBuilder()
+            .withShape(10, 10)
+            .withDataType(DataType.UINT32)
+            .withChunks(5, 5)
+            .withFillValue(1)
+            .build();
+        ucar.ma2.DataType ma2DataType = arrayMetadata.dataType.getMA2DataType();
+        Array array = Array.create(storeHandle, arrayMetadata);
+        array.write(new long[]{0, 0}, ucar.ma2.Array.factory(ma2DataType, new int[]{10, 10}, testData));
+
+        array = array.resize(new long[]{20, 15});
+        Assertions.assertArrayEquals(new int[]{20, 15}, array.read().getShape());
+
+        ucar.ma2.Array data = array.read(new long[]{0, 0}, new int[]{10, 10});
+        Assertions.assertArrayEquals(testData, (int[]) data.get1DJavaArray(ma2DataType));
+
+        data = array.read(new long[]{10, 10}, new int[]{5, 5});
+        int[] expectedData = new int[5 * 5];
+        Arrays.fill(expectedData, 1);
+        Assertions.assertArrayEquals(expectedData, (int[]) data.get1DJavaArray(ma2DataType));
+    }
+
+    @Test
+    public void testGroupAttributes() throws IOException, ZarrException {
+        StoreHandle storeHandle = new FilesystemStore(TESTOUTPUT).resolve("testGroupAttributesV2");
+
+        Group group = Group.create(storeHandle, new Attributes() {{
+            put("group_attr", "group_value");
+        }});
+
+        Assertions.assertEquals("group_value", group.metadata().attributes().getString("group_attr"));
+
+        group = Group.open(storeHandle);
+        Assertions.assertEquals("group_value", group.metadata().attributes().getString("group_attr"));
     }
 
 
diff --git a/src/test/java/dev/zarr/zarrjava/ZarrV3Test.java b/src/test/java/dev/zarr/zarrjava/ZarrV3Test.java
index cec859ac..846f770d 100644
--- a/src/test/java/dev/zarr/zarrjava/ZarrV3Test.java
+++ b/src/test/java/dev/zarr/zarrjava/ZarrV3Test.java
@@ -3,8 +3,7 @@
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import dev.zarr.zarrjava.v3.codec.Codec;
-import dev.zarr.zarrjava.v3.codec.core.BloscCodec;
-import dev.zarr.zarrjava.v3.codec.core.ShardingIndexedCodec;
+import dev.zarr.zarrjava.core.Attributes;
 
 import com.fasterxml.jackson.databind.JsonMappingException;
 import dev.zarr.zarrjava.store.*;
@@ -12,8 +11,7 @@
 import dev.zarr.zarrjava.v3.Node;
 import dev.zarr.zarrjava.v3.*;
 import dev.zarr.zarrjava.v3.codec.CodecBuilder;
-import dev.zarr.zarrjava.v3.codec.core.BytesCodec;
-import dev.zarr.zarrjava.v3.codec.core.TransposeCodec;
+import dev.zarr.zarrjava.v3.codec.core.*;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
@@ -517,7 +515,7 @@ public void testOpenOverloads() throws ZarrException, IOException {
     public void testGroup() throws IOException, ZarrException {
         FilesystemStore fsStore = new FilesystemStore(TESTOUTPUT);
 
-        Map<String, Object> attributes = new HashMap<>();
+        Attributes attributes = new Attributes();
         attributes.put("hello", "world");
 
         Group group = Group.create(fsStore.resolve("testgroup"));
@@ -559,20 +557,47 @@ public void testCreateGroup() throws ZarrException, IOException {
         StoreHandle storeHandle = new FilesystemStore(TESTOUTPUT).resolve("testCreateGroupV3");
         Path storeHandlePath = TESTOUTPUT.resolve("testCreateGroupV3Path");
         String storeHandleString = String.valueOf(TESTOUTPUT.resolve("testCreateGroupV3String"));
-        Map<String, Object> attributes = new HashMap<>();
+        Attributes attributes = new Attributes();
         attributes.put("hello", "world");
 
         Group group = Group.create(storeHandle, new GroupMetadata(attributes));
         Assertions.assertTrue(storeHandle.resolve("zarr.json").exists());
-        Assertions.assertEquals("world", group.metadata.attributes.get("hello"));
+        Assertions.assertEquals("world", group.metadata.attributes().get("hello"));
 
         group = Group.create(storeHandlePath, new GroupMetadata(attributes));
         Assertions.assertTrue(Files.exists(storeHandlePath.resolve("zarr.json")));
-        Assertions.assertEquals("world", group.metadata.attributes.get("hello"));
+        Assertions.assertEquals("world", group.metadata.attributes().get("hello"));
 
         group = Group.create(storeHandleString, new GroupMetadata(attributes));
         Assertions.assertTrue(Files.exists(Paths.get(storeHandleString).resolve("zarr.json")));
-        Assertions.assertEquals("world", group.metadata.attributes.get("hello"));
+        Assertions.assertEquals("world", group.metadata.attributes().get("hello"));
+    }
+
+    @Test
+    public void testAttributes() throws IOException, ZarrException {
+        StoreHandle storeHandle = new FilesystemStore(TESTOUTPUT).resolve("testAttributesV3");
+
+        ArrayMetadata arrayMetadata = Array.metadataBuilder()
+            .withShape(10, 10)
+            .withDataType(DataType.UINT8)
+            .withChunkShape(5, 5)
+            .putAttribute("specific", "attribute")
+            .withAttributes(defaultTestAttributes())
+            .withAttributes(new Attributes() {{
+                put("another", "attribute");
+            }})
+
+            .build();
+
+         Array array = Array.create(storeHandle, arrayMetadata);
+         assertContainsTestAttributes(array.metadata().attributes());
+         Assertions.assertEquals("attribute", array.metadata().attributes().getString("specific"));
+         Assertions.assertEquals("attribute", array.metadata().attributes().getString("another"));
+
+         Array arrayOpened = Array.open(storeHandle);
+         assertContainsTestAttributes(arrayOpened.metadata().attributes());
+         Assertions.assertEquals("attribute", arrayOpened.metadata().attributes().getString("specific"));
+         Assertions.assertEquals("attribute", arrayOpened.metadata().attributes().getString("another"));
     }
 
     @Test
@@ -602,6 +627,7 @@ static Stream<Function<CodecBuilder, CodecBuilder>> codecBuilders() {
                 CodecBuilder::withCrc32c
         );
     }
+
     static Stream<Function<ArrayMetadataBuilder, ArrayMetadataBuilder>> chunkKeyEncodingsAndCodecs() {
         Stream<Function<ArrayMetadataBuilder, ArrayMetadataBuilder>> builders = Stream.of(
                 ArrayMetadataBuilder::withDefaultChunkKeyEncoding,
@@ -611,7 +637,6 @@ static Stream<Function<ArrayMetadataBuilder, ArrayMetadataBuilder>> chunkKeyEnco
         return Stream.concat(builders, codecBuilders().map(codecFunc -> b -> b.withCodecs(codecFunc)));
     }
 
-
     @ParameterizedTest
     @MethodSource("chunkKeyEncodingsAndCodecs")
     public void testZarrJsonFormat(Function<ArrayMetadataBuilder, ArrayMetadataBuilder> chunkKeyEncodingsAndCodecs) throws ZarrException, IOException {
@@ -631,4 +656,79 @@ public void testZarrJsonFormat(Function<ArrayMetadataBuilder, ArrayMetadataBuild
             Assertions.assertEquals(JSON.toPrettyString(), jsonInString);
         }
     }
+
+    @Test
+    public void testSetAndUpdateAttributes() throws IOException, ZarrException {
+        StoreHandle storeHandle = new FilesystemStore(TESTOUTPUT).resolve("testSetAttributesV3");
+
+        ArrayMetadata arrayMetadata = Array.metadataBuilder()
+            .withShape(10, 10)
+            .withDataType(DataType.UINT8)
+            .withChunkShape(5, 5)
+            .withAttributes(new Attributes(b -> b.set("some", "value")))
+            .build();
+
+        Array array = Array.create(storeHandle, arrayMetadata);
+        Assertions.assertEquals("value", array.metadata().attributes().getString("some"));
+        array.setAttributes(defaultTestAttributes());
+        array = Array.open(storeHandle);
+        assertContainsTestAttributes(array.metadata().attributes());
+        Assertions.assertNull(array.metadata().attributes().get("some"));
+
+        // add attribute
+        array = array.updateAttributes(b -> b.set("new_attribute", "new_value"));
+        Assertions.assertEquals("new_value", array.metadata().attributes().getString("new_attribute"));
+        array = Array.open(storeHandle);
+        Assertions.assertEquals("new_value", array.metadata().attributes().getString("new_attribute"));
+
+        // delete attribute
+        array = array.updateAttributes(b -> b.delete("new_value"));
+        Assertions.assertNull(array.metadata().attributes().get("new_value"));
+        array = Array.open(storeHandle);
+        Assertions.assertNull(array.metadata().attributes().get("new_value"));
+
+        assertContainsTestAttributes(array.metadata().attributes());
+    }
+
+    @Test
+    public void testResizeArray() throws IOException, ZarrException {
+        int[] testData = new int[10 * 10];
+        Arrays.setAll(testData, p -> p);
+
+        StoreHandle storeHandle = new FilesystemStore(TESTOUTPUT).resolve("testResizeArrayV3");
+        ArrayMetadata arrayMetadata = Array.metadataBuilder()
+            .withShape(10, 10)
+            .withDataType(DataType.UINT32)
+            .withChunkShape(5, 5)
+            .withFillValue(1)
+            .build();
+        ucar.ma2.DataType ma2DataType = arrayMetadata.dataType.getMA2DataType();
+        Array array = Array.create(storeHandle, arrayMetadata);
+        array.write(new long[]{0, 0}, ucar.ma2.Array.factory(ma2DataType, new int[]{10, 10}, testData));
+
+        array = array.resize(new long[]{20, 15});
+        Assertions.assertArrayEquals(new int[]{20, 15}, array.read().getShape());
+
+        ucar.ma2.Array data = array.read(new long[]{0, 0}, new int[]{10, 10});
+        Assertions.assertArrayEquals(testData, (int[]) data.get1DJavaArray(ma2DataType));
+
+        data = array.read(new long[]{10, 10}, new int[]{5, 5});
+        int[] expectedData = new int[5 * 5];
+        Arrays.fill(expectedData, 1);
+        Assertions.assertArrayEquals(expectedData, (int[]) data.get1DJavaArray(ma2DataType));
+    }
+
+    @Test
+    public void testGroupAttributes() throws IOException, ZarrException {
+        StoreHandle storeHandle = new FilesystemStore(TESTOUTPUT).resolve("testGroupAttributesV3");
+
+        Group group = Group.create(storeHandle, new Attributes() {{
+            put("group_attr", "group_value");
+        }});
+
+        Assertions.assertEquals("group_value", group.metadata().attributes().getString("group_attr"));
+
+        group = Group.open(storeHandle);
+        Assertions.assertEquals("group_value", group.metadata().attributes().getString("group_attr"));
+    }
 }
diff --git a/src/test/python-scripts/zarr_python_group_v2.py b/src/test/python-scripts/zarr_python_group.py
similarity index 78%
rename from src/test/python-scripts/zarr_python_group_v2.py
rename to src/test/python-scripts/zarr_python_group.py
index 5052ddf0..3aa76c73 100644
--- a/src/test/python-scripts/zarr_python_group_v2.py
+++ b/src/test/python-scripts/zarr_python_group.py
@@ -7,16 +7,20 @@
 from zarr.storage import LocalStore
 
 store_path_read = Path(sys.argv[1])
+store_path_write = Path(sys.argv[2])
+zarr_format = int(sys.argv[3])
+assert zarr_format in (2,3), f"unexpected zarr format: {zarr_format}"
 
 expected_data = np.arange(16 * 16 * 16, dtype='int32').reshape(16, 16, 16)
 
-g = zarr.open_group(store=LocalStore(store_path_read), zarr_format=2)
+g = zarr.open_group(store=LocalStore(store_path_read), zarr_format=zarr_format)
+assert g.attrs['attr'] == 'value'
 a = g['group']['array']
 read_data = a[:, :]
 assert np.array_equal(read_data, expected_data), f"got:\n {read_data} \nbut expected:\n {expected_data}"
 
-store_path_write = Path(sys.argv[2])
-g2 = zarr.create_group(store=LocalStore(store_path_write), zarr_format=2)
+g2 = zarr.create_group(store=LocalStore(store_path_write), zarr_format=zarr_format)
+g2.attrs['attr'] = 'value'
 a2 = g2.create_group('group2').create_array(
     name='array2',
     shape=(16, 16, 16),
diff --git a/src/test/python-scripts/zarr_python_read_v2.py b/src/test/python-scripts/zarr_python_read_v2.py
index 5ff5e5a8..5d0b1c63 100644
--- a/src/test/python-scripts/zarr_python_read_v2.py
+++ b/src/test/python-scripts/zarr_python_read_v2.py
@@ -33,7 +33,7 @@
     filters=filters,
     serializer=serializer,
     compressors=compressor,
-#     attributes={'test_key': 'test_value'},
+    attributes={'test_key': 'test_value'},
 )
 
 assert a.metadata == b.metadata, f"not equal: \n{a.metadata=}\n{b.metadata=}"