diff --git a/implement-cowsay/cow.py b/implement-cowsay/cow.py
new file mode 100644
index 000000000..7aff7f3b9
--- /dev/null
+++ b/implement-cowsay/cow.py
@@ -0,0 +1,26 @@
+import argparse
+import cowsay
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Make animals say things")
+    parser.add_argument(
+        "--animal",
+        choices=cowsay.char_names,
+        default="cow",
+        help="The animal to be saying things."
+    )
+    parser.add_argument(
+        "message",
+        nargs="+",
+        help="The message to say."
+    )
+
+    args = parser.parse_args()
+    message = " ".join(args.message)
+
+    print(cowsay.get_output_string(args.animal, message))
+
+
+if __name__ == "__main__":
+    main()
\ No newline at end of file
diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
new file mode 100644
index 000000000..2da8c591d
--- /dev/null
+++ b/implement-shell-tools/cat/cat.js
@@ -0,0 +1,34 @@
+const fs = require("fs");
+
+const args = process.argv.slice(2);
+
+const showLineNumbers = args.includes("-n");
+const numberNonEmptyLines = args.includes("-b");
+
+const files = args.filter(arg => arg !== "-n" && arg !== "-b");
+
+for (const file of files) {
+  const content = fs.readFileSync(file, "utf8");
+
+  if (numberNonEmptyLines) {
+    const lines = content.split("\n");
+    let lineNumber = 1;
+
+    lines.forEach((line) => {
+      if (line.trim() !== "") {
+        console.log(`${lineNumber} ${line}`);
+        lineNumber++;
+      } else {
+        console.log(line);
+      }
+    });
+  } else if (showLineNumbers) {
+    const lines = content.split("\n");
+
+    lines.forEach((line, index) => {
+      console.log(`${index + 1} ${line}`);
+    });
+  } else {
+    process.stdout.write(content);
+  }
+}
\ No newline at end of file
diff --git a/implement-shell-tools/ls/ls.js b/implement-shell-tools/ls/ls.js
new file mode 100644
index 000000000..341ab34a2
--- /dev/null
+++ b/implement-shell-tools/ls/ls.js
@@ -0,0 +1,21 @@
+const fs = require("fs");
+
+const args = process.argv.slice(2);
+
+const showAll = args.includes("-a");
+
+// remove -a from arguments
+const filteredArgs = args.filter(arg => arg !== "-a");
+
+const target = filteredArgs[0] || ".";
+
+let files = fs.readdirSync(target);
+
+// hide hidden files if -a is NOT used
+if (!showAll) {
+  files = files.filter(file => !file.startsWith("."));
+}
+
+files.forEach(file => {
+  console.log(file);
+});
\ No newline at end of file
diff --git a/implement-shell-tools/wc/wc.js b/implement-shell-tools/wc/wc.js
new file mode 100644
index 000000000..ee89ff398
--- /dev/null
+++ b/implement-shell-tools/wc/wc.js
@@ -0,0 +1,29 @@
+const fs = require("fs");
+
+const args = process.argv.slice(2);
+
+const showLines = args.includes("-l");
+const showWords = args.includes("-w");
+const showChars = args.includes("-c");
+
+const files = args.filter(
+  (arg) => arg !== "-l" && arg !== "-w" && arg !== "-c"
+);
+
+for (const file of files) {
+  const content = fs.readFileSync(file, "utf8");
+
+  const lines = content.split("\n").length;
+  const words = content.trim().split(/\s+/).length;
+  const chars = content.length;
+
+  if (showLines) {
+    console.log(lines, file);
+  } else if (showWords) {
+    console.log(words, file);
+  } else if (showChars) {
+    console.log(chars, file);
+  } else {
+    console.log(lines, words, chars, file);
+  }
+}
\ No newline at end of file