diff --git a/main.py b/main.py
index a408731a..8e37f0bc 100644
--- a/main.py
+++ b/main.py
@@ -1,55 +1,54 @@
 import json
+from typing import Dict, List
 
 import quart
 import quart_cors
-from quart import request
+from quart import Quart, Response, jsonify, request
 
-app = quart_cors.cors(quart.Quart(__name__), allow_origin="https://chat.openai.com")
+app = quart_cors.cors(Quart(__name__), allow_origin="https://chat.openai.com")
 
 # Keep track of todo's. Does not persist if Python session is restarted.
-_TODOS = {}
+_TODOS: Dict[str, List[str]] = {}
 
 @app.post("/todos/<string:username>")
-async def add_todo(username):
-    request = await quart.request.get_json(force=True)
+async def add_todo(username: str) -> Response:
+    data = await request.get_json(force=True)
     if username not in _TODOS:
         _TODOS[username] = []
-    _TODOS[username].append(request["todo"])
-    return quart.Response(response='OK', status=200)
+    _TODOS[username].append(data["todo"])
+    return Response(response='OK', status=200)
 
 @app.get("/todos/<string:username>")
-async def get_todos(username):
-    return quart.Response(response=json.dumps(_TODOS.get(username, [])), status=200)
+async def get_todos(username: str) -> Response:
+    return jsonify(_TODOS.get(username) or [])
 
 @app.delete("/todos/<string:username>")
-async def delete_todo(username):
-    request = await quart.request.get_json(force=True)
-    todo_idx = request["todo_idx"]
+async def delete_todo(username: str) -> Response:
+    data = await request.get_json(force=True)
+    todo_idx = data["todo_idx"]
     # fail silently, it's a simple plugin
-    if 0 <= todo_idx < len(_TODOS[username]):
+    if 0 <= todo_idx < len(_TODOS.get(username, [])):
         _TODOS[username].pop(todo_idx)
-    return quart.Response(response='OK', status=200)
+    return Response(response='OK', status=200)
 
 @app.get("/logo.png")
-async def plugin_logo():
+async def plugin_logo() -> Response:
     filename = 'logo.png'
     return await quart.send_file(filename, mimetype='image/png')
 
 @app.get("/.well-known/ai-plugin.json")
-async def plugin_manifest():
-    host = request.headers['Host']
+async def plugin_manifest() -> Response:
     with open("./.well-known/ai-plugin.json") as f:
         text = f.read()
-        return quart.Response(text, mimetype="text/json")
+    return Response(text, mimetype="text/json")
 
 @app.get("/openapi.yaml")
-async def openapi_spec():
-    host = request.headers['Host']
+async def openapi_spec() -> Response:
     with open("openapi.yaml") as f:
         text = f.read()
-        return quart.Response(text, mimetype="text/yaml")
+    return Response(text, mimetype="text/yaml")
 
-def main():
+def main() -> None:
     app.run(debug=True, host="0.0.0.0", port=5003)
 
 if __name__ == "__main__":