diff --git a/01-hello/src/entry.py b/01-hello/src/entry.py
index 8bdd647..ecc7a07 100644
--- a/01-hello/src/entry.py
+++ b/01-hello/src/entry.py
@@ -1,4 +1,4 @@
-from workers import WorkerEntrypoint, Response
+from workers import Response, WorkerEntrypoint
 
 
 class Default(WorkerEntrypoint):
diff --git a/02-binding/src/entry.py b/02-binding/src/entry.py
index cbbba4f..098c7b5 100644
--- a/02-binding/src/entry.py
+++ b/02-binding/src/entry.py
@@ -1,4 +1,4 @@
-from workers import WorkerEntrypoint, Response
+from workers import Response, WorkerEntrypoint
 
 
 class Default(WorkerEntrypoint):
diff --git a/04-query-d1/src/entry.py b/04-query-d1/src/entry.py
index c9709ac..8366720 100644
--- a/04-query-d1/src/entry.py
+++ b/04-query-d1/src/entry.py
@@ -1,4 +1,4 @@
-from workers import WorkerEntrypoint, Response
+from workers import Response, WorkerEntrypoint
 
 
 class Default(WorkerEntrypoint):
diff --git a/05-langchain/src/worker.py b/05-langchain/src/worker.py
index 0a38e47..922edb8 100644
--- a/05-langchain/src/worker.py
+++ b/05-langchain/src/worker.py
@@ -1,6 +1,6 @@
-from workers import WorkerEntrypoint, Response
 from langchain_core.prompts import PromptTemplate
 from langchain_openai import OpenAI
+from workers import Response, WorkerEntrypoint
 
 
 class Default(WorkerEntrypoint):
diff --git a/07-durable-objects/src/entry.py b/07-durable-objects/src/entry.py
index 77a1fea..505924f 100644
--- a/07-durable-objects/src/entry.py
+++ b/07-durable-objects/src/entry.py
@@ -1,7 +1,8 @@
-from workers import WorkerEntrypoint, Response, DurableObject
-from pyodide.ffi import to_js
 from urllib.parse import urlparse
 
+from pyodide.ffi import to_js
+from workers import DurableObject, Response, WorkerEntrypoint
+
 
 class List(DurableObject):
     async def get_messages(self):
diff --git a/08-cron/src/entry.py b/08-cron/src/entry.py
index 41dd5f4..5ffc71e 100644
--- a/08-cron/src/entry.py
+++ b/08-cron/src/entry.py
@@ -1,4 +1,4 @@
-from workers import WorkerEntrypoint, Response
+from workers import Response, WorkerEntrypoint
 
 
 class Default(WorkerEntrypoint):
diff --git a/09-workers-ai/src/entry.py b/09-workers-ai/src/entry.py
index 42fd6d3..5c5e5b8 100644
--- a/09-workers-ai/src/entry.py
+++ b/09-workers-ai/src/entry.py
@@ -1,4 +1,4 @@
-from workers import WorkerEntrypoint, Response
+from workers import Response, WorkerEntrypoint
 
 
 class Default(WorkerEntrypoint):
diff --git a/10-workflows/src/entry.py b/10-workflows/src/entry.py
index fd47672..afad0c9 100644
--- a/10-workflows/src/entry.py
+++ b/10-workflows/src/entry.py
@@ -1,7 +1,8 @@
-from workers import WorkerEntrypoint, Response, WorkflowEntrypoint
-from urllib.parse import urlparse
 import asyncio
 import random
+from urllib.parse import urlparse
+
+from workers import Response, WorkerEntrypoint, WorkflowEntrypoint
 
 
 class DAGWorkflow(WorkflowEntrypoint):
diff --git a/11-opengraph/src/entry.py b/11-opengraph/src/entry.py
index 4b7f3a5..4168ecc 100644
--- a/11-opengraph/src/entry.py
+++ b/11-opengraph/src/entry.py
@@ -1,9 +1,9 @@
-from workers import WorkerEntrypoint, Request, fetch
-from js import HTMLRewriter
-from urllib.parse import urlparse
 from html import escape
+from urllib.parse import urlparse
 
+from js import HTMLRewriter
 from pyodide.ffi import create_proxy
+from workers import Request, WorkerEntrypoint, fetch
 
 
 class MetaTagInjector:
diff --git a/12-image-gen/src/entry.py b/12-image-gen/src/entry.py
index 1bad378..cfd1666 100644
--- a/12-image-gen/src/entry.py
+++ b/12-image-gen/src/entry.py
@@ -1,11 +1,11 @@
-from workers import WorkerEntrypoint, Response, Request
-from PIL import Image, ImageDraw, ImageFont
-from io import BytesIO
-from urllib.parse import urlparse, parse_qs
 import random
+from io import BytesIO
 from pathlib import Path
+from urllib.parse import parse_qs, urlparse
 
+from PIL import Image, ImageDraw, ImageFont
 from pyodide.ffi import to_js
+from workers import Request, Response, WorkerEntrypoint
 
 
 class Default(WorkerEntrypoint):
@@ -65,9 +65,9 @@ def generate_gradient(self, params: dict) -> Response:
         color2 = params.get("color2", [None])[0]
 
         if not color1:
-            color1 = "#{:06x}".format(random.randint(0, 0xFFFFFF))
+            color1 = f"#{random.randint(0, 0xFFFFFF):06x}"
         if not color2:
-            color2 = "#{:06x}".format(random.randint(0, 0xFFFFFF))
+            color2 = f"#{random.randint(0, 0xFFFFFF):06x}"
 
         # Convert hex colors to RGB tuples
         r1, g1, b1 = self.hex_to_rgb(color1)
diff --git a/13-js-api-pygments/py/src/entry.py b/13-js-api-pygments/py/src/entry.py
index feaa166..9817e01 100644
--- a/13-js-api-pygments/py/src/entry.py
+++ b/13-js-api-pygments/py/src/entry.py
@@ -1,8 +1,8 @@
-from workers import WorkerEntrypoint, Response, Request
 from pygments import highlight
-from pygments.lexers import get_lexer_by_name, guess_lexer
 from pygments.formatters import HtmlFormatter
+from pygments.lexers import get_lexer_by_name, guess_lexer
 from pygments.util import ClassNotFound
+from workers import Request, Response, WorkerEntrypoint
 
 
 class Default(WorkerEntrypoint):
diff --git a/14-websocket-stream-consumer/src/entry.py b/14-websocket-stream-consumer/src/entry.py
index 77b6427..ce158ee 100644
--- a/14-websocket-stream-consumer/src/entry.py
+++ b/14-websocket-stream-consumer/src/entry.py
@@ -1,10 +1,11 @@
-from workers import WorkerEntrypoint, Response, DurableObject
-import js
 import json
 import time
-from pyodide.ffi import create_proxy
 from urllib.parse import urlparse
 
+import js
+from pyodide.ffi import create_proxy
+from workers import DurableObject, Response, WorkerEntrypoint
+
 
 class BlueskyFirehoseConsumer(DurableObject):
     """Durable Object that maintains a persistent WebSocket connection to Bluesky Jetstream."""
diff --git a/15-chatroom/src/entry.py b/15-chatroom/src/entry.py
index a08ebd7..80a14a7 100644
--- a/15-chatroom/src/entry.py
+++ b/15-chatroom/src/entry.py
@@ -1,9 +1,10 @@
-from workers import WorkerEntrypoint, Response, DurableObject
-from pathlib import Path
-from js import WebSocketPair
 import json
+from datetime import UTC, datetime
+from pathlib import Path
 from urllib.parse import urlparse
-from datetime import datetime, timezone
+
+from js import WebSocketPair
+from workers import DurableObject, Response, WorkerEntrypoint
 
 
 class Chatroom(DurableObject):
@@ -95,7 +96,7 @@ def broadcast(self, message):
 
     def get_timestamp(self):
         """Get current timestamp in ISO format."""
-        return datetime.now(timezone.utc).isoformat()
+        return datetime.now(UTC).isoformat()
 
 
 class Default(WorkerEntrypoint):
diff --git a/17-dynamic-py-py/src/entry.py b/17-dynamic-py-py/src/entry.py
index 91b1dba..e53d4f5 100644
--- a/17-dynamic-py-py/src/entry.py
+++ b/17-dynamic-py-py/src/entry.py
@@ -1,5 +1,5 @@
-from pyodide.ffi import create_proxy, to_js
 from js import Object
+from pyodide.ffi import create_proxy, to_js
 from workers import WorkerEntrypoint
 
 # The source code of the dynamically-loaded Python Worker. In a real
diff --git a/pyproject.toml b/pyproject.toml
index 171d7cb..796e6f6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -13,3 +13,31 @@ dev = [
     "requests>=2.32.5",
     "ruff>=0.12.10",
 ]
+
+[tool.ruff]
+target-version = "py312"
+extend-exclude = ["**/python_modules", "**/.venv-workers"]
+
+[tool.ruff.lint]
+select = [
+    "B0",   # flake8-bugbear
+    "C4",   # flake8-comprehensions
+    "E",    # pycodestyle errors
+    "F",    # pyflakes
+    "I",    # isort
+    "PGH",  # pygrep-hooks
+    "UP",   # pyupgrade
+    "W",    # pycodestyle warnings
+]
+ignore = [
+    "E501",  # line length is handled by the formatter
+]
+
+[tool.ruff.lint.isort]
+# Supplied by the Workers runtime rather than PyPI, so ruff cannot resolve them
+# and would otherwise infer their section from whatever happens to be on disk.
+known-third-party = ["asgi", "js", "pyodide", "workers"]
+
+[tool.ruff.lint.per-file-ignores]
+# `js` and `pyodide` imports resolve only at runtime inside Pyodide.
+"*/src/*.py" = ["E402"]
diff --git a/tests/conftest.py b/tests/conftest.py
index fafe74e..3ab5770 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,12 +1,12 @@
 import os
-import subprocess
-import time
 import socket
+import subprocess
 import sys
-import pytest
+import time
+from contextlib import contextmanager
 from pathlib import Path
 
-from contextlib import contextmanager
+import pytest
 
 REPO_ROOT = Path(__file__).parents[1]
 
diff --git a/tests/test_examples.py b/tests/test_examples.py
index 49f5ce4..e4b2b1a 100644
--- a/tests/test_examples.py
+++ b/tests/test_examples.py
@@ -1,6 +1,7 @@
-import requests
-import pytest
 import subprocess
+
+import pytest
+import requests
 from conftest import REPO_ROOT