diff --git a/haystack/utils/http_client.py b/haystack/utils/http_client.py
index 61d323172c3..7b198e4c4a6 100644
--- a/haystack/utils/http_client.py
+++ b/haystack/utils/http_client.py
@@ -7,22 +7,14 @@
 import httpx
 
 
-@overload
-def init_http_client(http_client_kwargs: dict[str, Any], async_client: Literal[False]) -> httpx.Client: ...
 @overload
 def init_http_client(
-    http_client_kwargs: dict[str, Any] | None, async_client: Literal[False]
+    http_client_kwargs: dict[str, Any] | None = ..., async_client: Literal[False] = ...
 ) -> httpx.Client | None: ...
 @overload
-def init_http_client(http_client_kwargs: dict[str, Any], async_client: Literal[True]) -> httpx.AsyncClient: ...
-@overload
 def init_http_client(
-    http_client_kwargs: dict[str, Any] | None, async_client: Literal[True]
+    http_client_kwargs: dict[str, Any] | None = ..., async_client: Literal[True] = ...
 ) -> httpx.AsyncClient | None: ...
-@overload
-def init_http_client(
-    http_client_kwargs: dict[str, Any] | None, async_client: bool
-) -> httpx.Client | httpx.AsyncClient | None: ...
 def init_http_client(
     http_client_kwargs: dict[str, Any] | None = None, async_client: bool = False
 ) -> httpx.Client | httpx.AsyncClient | None:
diff --git a/pyproject.toml b/pyproject.toml
index d83e959829c..1b8da4e9367 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -163,7 +163,7 @@ integration-only-slow = 'pytest --maxfail=5 -m "integration and slow" {args:test
 all = 'pytest {args:test}'
 
 # TODO We want to eventually type the whole test folder
-types = "mypy --install-types --non-interactive --cache-dir=.mypy_cache/ {args:haystack test/core/ test/marshal/ test/testing/ test/tracing/ test/tools/ test/human_in_the_loop test/evaluation test/document_stores test/dataclasses}"
+types = "mypy --install-types --non-interactive --cache-dir=.mypy_cache/ {args:haystack test/core/ test/marshal/ test/testing/ test/tracing/ test/tools/ test/human_in_the_loop test/evaluation test/document_stores test/dataclasses test/utils/}"
 
 [tool.hatch.envs.e2e]
 template = "test"
diff --git a/test/utils/test_auth.py b/test/utils/test_auth.py
index a7b40424ffe..2445655fe90 100644
--- a/test/utils/test_auth.py
+++ b/test/utils/test_auth.py
@@ -32,9 +32,9 @@ def test_token_secret():
         Secret.from_token("")
 
     with pytest.raises(FrozenInstanceError):
-        secret._token = "abba"
+        secret._token = "abba"  # type: ignore[misc]
     with pytest.raises(FrozenInstanceError):
-        secret._type = SecretType.ENV_VAR
+        secret._type = SecretType.ENV_VAR  # type: ignore[misc]
 
 
 def test_env_var_secret():
@@ -52,10 +52,12 @@ def test_env_var_secret():
         secret.resolve_value()
 
     secret = Secret.from_env_var("TEST_ENV_VAR2", strict=False)
+    assert isinstance(secret, EnvVarSecret)
     assert secret._strict is False
     assert secret.resolve_value() is None
 
     secret = Secret.from_env_var(["TEST_ENV_VAR2", "TEST_ENV_VAR1"], strict=True)
+    assert isinstance(secret, EnvVarSecret)
     assert secret._env_vars == ("TEST_ENV_VAR2", "TEST_ENV_VAR1")
     with pytest.raises(ValueError, match="None of the following .* variables are set"):
         secret.resolve_value()
@@ -73,8 +75,8 @@ def test_env_var_secret():
     )
 
     with pytest.raises(FrozenInstanceError):
-        secret._env_vars = ("A", "B")
+        secret._env_vars = ("A", "B")  # type: ignore[misc]
     with pytest.raises(FrozenInstanceError):
-        secret._strict = False
+        secret._strict = False  # type: ignore[misc]
     with pytest.raises(FrozenInstanceError):
-        secret._type = SecretType.TOKEN
+        secret._type = SecretType.TOKEN  # type: ignore[misc]
diff --git a/test/utils/test_callable_serialization.py b/test/utils/test_callable_serialization.py
index c39acafe655..3f007f45ad3 100644
--- a/test/utils/test_callable_serialization.py
+++ b/test/utils/test_callable_serialization.py
@@ -11,7 +11,7 @@
 from haystack.utils import deserialize_callable, serialize_callable
 
 
-def some_random_callable_for_testing(some_ignored_arg: str):
+def some_random_callable_for_testing(some_ignored_arg: str) -> None:
     pass
 
 
diff --git a/test/utils/test_device.py b/test/utils/test_device.py
index abd74827d2d..2d7c1b7d889 100644
--- a/test/utils/test_device.py
+++ b/test/utils/test_device.py
@@ -57,7 +57,7 @@ def test_device_map():
     )
 
     with pytest.raises(TypeError, match="unexpected device"):
-        DeviceMap.from_hf({"layer1": 0.1})
+        DeviceMap.from_hf({"layer1": 0.1})  # type: ignore[dict-item]
 
     assert device_map.first_device == Device.gpu(0)
     assert DeviceMap({}).first_device is None
diff --git a/test/utils/test_experimental.py b/test/utils/test_experimental.py
index 257d3252ace..627f241ad87 100644
--- a/test/utils/test_experimental.py
+++ b/test/utils/test_experimental.py
@@ -39,7 +39,7 @@ class MyComponent:
             def run(self, value: int) -> dict:
                 return {"value": value}
 
-        assert MyComponent.__experimental__ is True
+        assert getattr(MyComponent, "__experimental__") is True  # noqa: B009
 
     def test_passes_args_and_kwargs_to_init(self):
         @_experimental
diff --git a/test/utils/test_hf.py b/test/utils/test_hf.py
index c3e12b9f4e3..1c0498d5c00 100644
--- a/test/utils/test_hf.py
+++ b/test/utils/test_hf.py
@@ -59,7 +59,7 @@ def test_convert_message_to_hf_format():
         "tool_calls": [{"type": "function", "function": {"name": "weather", "arguments": {"city": "Paris"}}}],
     }
 
-    tool_result = {"weather": "sunny", "temperature": "25"}
+    tool_result = '{"weather": "sunny", "temperature": "25"}'
     message = ChatMessage.from_tool(
         tool_result=tool_result, origin=ToolCall(id="123", tool_name="weather", arguments={"city": "Paris"})
     )
@@ -83,7 +83,7 @@ def test_convert_message_to_hf_invalid():
             ToolCallResult(
                 result="result!",
                 origin=ToolCall(id="123", tool_name="weather", arguments={"city": "Paris"}),
-                error=None,
+                error=None,  # type: ignore[arg-type]
             ),
         ],
     )
diff --git a/test/utils/test_http_client.py b/test/utils/test_http_client.py
index 8c52c265b2a..43c4c2496c1 100644
--- a/test/utils/test_http_client.py
+++ b/test/utils/test_http_client.py
@@ -14,7 +14,8 @@ def test_init_http_client():
     assert http_client is None
 
     # test client is initialized with http_client_kwargs
-    http_client = init_http_client(http_client_kwargs={"base_url": "https://example.com"})
+    client_kwargs = {"base_url": "https://example.com"}
+    http_client = init_http_client(http_client_kwargs=client_kwargs)
     assert http_client is not None
     assert isinstance(http_client, httpx.Client)
     assert http_client.base_url == "https://example.com"
@@ -35,7 +36,7 @@ def test_init_http_client_async():
 def test_http_client_kwargs_type_validation():
     # test http_client_kwargs is not a dictionary
     with pytest.raises(TypeError, match="The parameter 'http_client_kwargs' must be a dictionary."):
-        init_http_client(http_client_kwargs="invalid")
+        init_http_client(http_client_kwargs="invalid")  # type: ignore[call-overload]
 
 
 def test_http_client_kwargs_with_invalid_params():
diff --git a/test/utils/test_jinja2_chat_extension.py b/test/utils/test_jinja2_chat_extension.py
index 48e4edf3eea..0c2ec086d96 100644
--- a/test/utils/test_jinja2_chat_extension.py
+++ b/test/utils/test_jinja2_chat_extension.py
@@ -4,6 +4,7 @@
 
 import base64
 import json
+from typing import Any
 from unittest.mock import patch
 
 import pytest
@@ -97,7 +98,12 @@ def test_system_message(self, jinja_env):
         """
         rendered = jinja_env.from_string(template).render()
         output = json.loads(rendered.strip())
-        expected = {"role": "system", "content": [{"text": "You are a helpful assistant."}], "name": None, "meta": {}}
+        expected: dict[str, Any] = {
+            "role": "system",
+            "content": [{"text": "You are a helpful assistant."}],
+            "name": None,
+            "meta": {},
+        }
         assert output == expected
 
     def test_user_message_with_variable(self, jinja_env):
@@ -108,7 +114,12 @@ def test_user_message_with_variable(self, jinja_env):
         """
         rendered = jinja_env.from_string(template).render(name="Alice")
         output = json.loads(rendered.strip())
-        expected = {"role": "user", "content": [{"text": "Hello, my name is Alice!"}], "name": None, "meta": {}}
+        expected: dict[str, Any] = {
+            "role": "user",
+            "content": [{"text": "Hello, my name is Alice!"}],
+            "name": None,
+            "meta": {},
+        }
         assert output == expected
 
     def test_assistant_message_with_tool_call(self, jinja_env):
@@ -121,7 +132,7 @@ def test_assistant_message_with_tool_call(self, jinja_env):
         tool_call = ToolCall(tool_name="search", arguments={"query": "an interesting question"}, id="search_1")
         rendered = jinja_env.from_string(template).render(tool_call=tool_call)
         output = json.loads(rendered.strip())
-        expected = {
+        expected: dict[str, Any] = {
             "role": "assistant",
             "content": [
                 {"text": "Let me search for that information."},
@@ -149,7 +160,7 @@ def test_assistant_message_with_reasoning(self, jinja_env):
         reasoning = ReasoningContent(reasoning_text="Let me think about it...", extra={"key": "value"})
         rendered = jinja_env.from_string(template).render(reasoning=reasoning)
         output = json.loads(rendered.strip())
-        expected = {
+        expected: dict[str, Any] = {
             "role": "assistant",
             "content": [
                 {"reasoning": {"reasoning_text": "Let me think about it...", "extra": {"key": "value"}}},
@@ -170,7 +181,7 @@ def test_tool_message(self, jinja_env):
         tool_result = ToolCallResult(result="Here are the search results", origin=tool_call, error=False)
         rendered = jinja_env.from_string(template).render(tool_result=tool_result)
         output = json.loads(rendered.strip())
-        expected = {
+        expected: dict[str, Any] = {
             "role": "tool",
             "content": [
                 {
@@ -208,7 +219,7 @@ def test_tool_message_tool_call_result_list(self, jinja_env, base64_image_string
         )
         rendered = jinja_env.from_string(template).render(tool_result=tool_result)
         output = json.loads(rendered.strip())
-        expected = {
+        expected: dict[str, Any] = {
             "role": "tool",
             "content": [
                 {
@@ -250,7 +261,7 @@ def test_user_message_with_image(self, jinja_env, base64_image_string):
         image = ImageContent(base64_image=base64_image_string, mime_type="image/png")
         rendered = jinja_env.from_string(template).render(image=image)
         output = json.loads(rendered.strip())
-        expected = {
+        expected: dict[str, Any] = {
             "role": "user",
             "content": [
                 {"text": "Please describe this image:"},
@@ -284,7 +295,7 @@ def test_user_message_with_multiple_images(self, jinja_env, base64_image_string)
         ]
         rendered = jinja_env.from_string(template).render(images=images)
         output = json.loads(rendered.strip())
-        expected = {
+        expected: dict[str, Any] = {
             "role": "user",
             "content": [
                 {"text": "Compare these images:"},
@@ -331,7 +342,7 @@ def test_user_message_with_multiple_images_and_interleaved_text(self, jinja_env,
         rendered = jinja_env.from_string(template).render(images=[image, image])
         output = json.loads(rendered.strip())
 
-        expected = {
+        expected: dict[str, Any] = {
             "role": "user",
             "content": [
                 {"text": "Image 1:"},
@@ -372,7 +383,7 @@ def test_user_message_with_file_content(self, jinja_env, base64_pdf_string):
         rendered = jinja_env.from_string(template).render(file=file)
         output = json.loads(rendered.strip())
 
-        expected = {
+        expected: dict[str, Any] = {
             "role": "user",
             "content": [
                 {"text": "Please describe this document:"},
@@ -402,7 +413,7 @@ def test_user_message_multiple_lines(self, jinja_env):
         """
         rendered = jinja_env.from_string(template).render()
         output = json.loads(rendered.strip())
-        expected = {
+        expected: dict[str, Any] = {
             "role": "user",
             "content": [
                 {
@@ -428,7 +439,7 @@ def test_invalid_role(self, jinja_env):
 
     def test_templatize_part_filter_with_invalid_type(self, jinja_env):
         with pytest.raises(TypeError, match="Unsupported type in ChatMessage content"):
-            templatize_part(jinja_env, 123)
+            templatize_part(jinja_env, 123)  # type: ignore[arg-type]
 
     def test_empty_message_content_raises_error(self, jinja_env):
         error_message = "Message content in template is empty or contains only whitespace characters."
@@ -482,7 +493,7 @@ def test_message_with_whitespace_handling(self, jinja_env):
             {% endmessage %}""",
             """{% message role="user" %}\tString\t{% endmessage %}""",
         ]
-        expected = {"role": "user", "content": [{"text": "String"}], "name": None, "meta": {}}
+        expected: dict[str, Any] = {"role": "user", "content": [{"text": "String"}], "name": None, "meta": {}}
         for template in templates:
             rendered = jinja_env.from_string(template).render()
             output = json.loads(rendered.strip())
diff --git a/test/utils/test_jinja2_extensions.py b/test/utils/test_jinja2_extensions.py
index 0d1dd09770d..e578d444994 100644
--- a/test/utils/test_jinja2_extensions.py
+++ b/test/utils/test_jinja2_extensions.py
@@ -2,7 +2,7 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
-from unittest.mock import patch
+from unittest.mock import MagicMock, patch
 
 import arrow
 import pytest
@@ -26,7 +26,7 @@ def jinja_extension(self, jinja_env: Environment) -> Jinja2TimeExtension:
         return Jinja2TimeExtension(jinja_env)
 
     @patch("haystack.utils.jinja2_extensions.arrow_import")
-    def test_init_fails_without_arrow(self, arrow_import_mock) -> None:
+    def test_init_fails_without_arrow(self, arrow_import_mock: MagicMock) -> None:
         arrow_import_mock.check.side_effect = ImportError
         with pytest.raises(ImportError):
             Jinja2TimeExtension(Environment())
diff --git a/test/utils/test_misc.py b/test/utils/test_misc.py
index 2e241a872dc..4e2286dea8a 100644
--- a/test/utils/test_misc.py
+++ b/test/utils/test_misc.py
@@ -70,6 +70,7 @@ def test_scores_decrease_with_rank(self):
         docs = [Document(id="a"), Document(id="b"), Document(id="c")]
         result = _reciprocal_rank_fusion([docs])
         by_id = {doc.id: doc.score for doc in result}
+        assert by_id["a"] is not None and by_id["b"] is not None and by_id["c"] is not None
         assert by_id["a"] > by_id["b"] > by_id["c"]
 
     def test_deduplicates_across_lists(self):
@@ -85,6 +86,7 @@ def test_higher_ranked_doc_gets_higher_score(self):
         result = _reciprocal_rank_fusion([docs_a, docs_b])
         by_id = {doc.id: doc.score for doc in result}
         # "a" is ranked 1st and 2nd; "c" is ranked 3rd and 1st — "a" should win
+        assert by_id["a"] is not None and by_id["c"] is not None
         assert by_id["a"] > by_id["c"]
 
     def test_equal_weights_by_default(self):
@@ -103,6 +105,7 @@ def test_weights_influence_scores(self):
         weighted_by_id = {doc.id: doc.score for doc in result_weighted}
         # with equal weights both docs score the same; with heavy weight on list_a, "a" should outscore "b"
         assert equal_by_id["a"] == pytest.approx(equal_by_id["b"])
+        assert weighted_by_id["a"] is not None and weighted_by_id["b"] is not None
         assert weighted_by_id["a"] > weighted_by_id["b"]
 
 
diff --git a/test/utils/test_requests_utils.py b/test/utils/test_requests_utils.py
index fd6de9b302d..9bf621268ae 100644
--- a/test/utils/test_requests_utils.py
+++ b/test/utils/test_requests_utils.py
@@ -104,10 +104,10 @@ def raise_for_status():
                         "Service Unavailable", request=error_response.request, response=error_response
                     )
 
-            error_response.raise_for_status = raise_for_status
+            error_response.raise_for_status = raise_for_status  # type: ignore[method-assign]
 
             success_response = httpx.Response(status_code=200, request=httpx.Request("GET", "https://example.com"))
-            success_response.raise_for_status = lambda: None
+            success_response.raise_for_status = lambda: None  # type: ignore[method-assign, assignment, return-value]
 
             with patch("httpx.Client.request") as mock_request:
                 # First call returns error status code, second call succeeds
@@ -218,10 +218,10 @@ def raise_for_status():
                         "Service Unavailable", request=error_response.request, response=error_response
                     )
 
-            error_response.raise_for_status = raise_for_status
+            error_response.raise_for_status = raise_for_status  # type: ignore[method-assign]
 
             success_response = httpx.Response(status_code=200, request=httpx.Request("GET", "https://example.com"))
-            success_response.raise_for_status = lambda: None
+            success_response.raise_for_status = lambda: None  # type: ignore[method-assign, assignment, return-value]
 
             with patch("httpx.AsyncClient.request") as mock_request:
                 # First call returns error status code, second call succeeds
diff --git a/test/utils/test_type_serialization.py b/test/utils/test_type_serialization.py
index b4b7536517b..913e22538fc 100644
--- a/test/utils/test_type_serialization.py
+++ b/test/utils/test_type_serialization.py
@@ -148,7 +148,7 @@ def test_output_type_deserialization():
     assert deserialize_type("float") == float
     assert deserialize_type("bool") == bool
     assert deserialize_type("None") is None
-    assert deserialize_type("NoneType") == type(None)  # type: ignore
+    assert deserialize_type("NoneType") == type(None)
 
 
 def test_output_builtin_type_deserialization():
@@ -198,10 +198,10 @@ def test_output_type_deserialization_nested():
 def test_output_type_serialization_typing_generic_with_nonetype():
     # NoneType used as a regular argument of a typing generic (not the implicit None of Optional)
     # must be kept, otherwise the serialized type is malformed (e.g. "typing.Dict[str]") or loses information.
-    assert serialize_type(Dict[str, type(None)]) == "typing.Dict[str, None]"
-    assert serialize_type(Dict[type(None), str]) == "typing.Dict[None, str]"
+    assert serialize_type(Dict[str, type(None)]) == "typing.Dict[str, None]"  # type: ignore[misc]
+    assert serialize_type(Dict[type(None), str]) == "typing.Dict[None, str]"  # type: ignore[misc]
     assert serialize_type(Tuple[int, type(None)]) == "typing.Tuple[int, None]"
-    assert serialize_type(List[type(None)]) == "typing.List[None]"
+    assert serialize_type(List[type(None)]) == "typing.List[None]"  # type: ignore[misc]
     # A Union with more than two members that includes None must keep None as well.
     assert serialize_type(Union[str, int, None]) == "typing.Union[str, int, None]"
     # Optional must still be serialized without a redundant trailing None.
@@ -210,10 +210,10 @@ def test_output_type_serialization_typing_generic_with_nonetype():
 
 def test_output_type_round_trip_typing_generic_with_nonetype():
     for type_ in [
-        Dict[str, type(None)],
-        Dict[type(None), str],
+        Dict[str, type(None)],  # type: ignore[misc]
+        Dict[type(None), str],  # type: ignore[misc]
         Tuple[int, type(None)],
-        List[type(None)],
+        List[type(None)],  # type: ignore[misc]
         Union[str, int, None],
         Optional[str],
     ]: