Tornado (web server)

Tornado
Original author	FriendFeed
Developers	Ben Darnell and FriendFeed engineering team
Initial release	2009 (2009)
Stable release	6.5.61  / 27 May 2026 (27 May 2026)
Written in	Python
Operating system	Cross-platform
Available in	English
Type	Web server
License	Apache License 2.0
Website	www.tornadoweb.org
Repository	github.com/tornadoweb/tornado

Tornado is a scalable, non-blocking web server and web application framework written in Python.² It was developed for use by FriendFeed; the company was acquired by Facebook in 2009 and Tornado was open-sourced soon after.³

Tornado is noted for its high performance. Its design enables handling a large number of concurrent connections (i.e., tries to solve the "C10k problem").

• An asynchronous MongoDB driver called Motor.
• CouchDB drivers called corduroy and trombi.
• Asynchronous driver for PostgreSQL wrapping psycopg called Momoko

The following code shows a simple web application that displays "Hello World!" when visited:⁴

import asyncio

import tornado.web

class MainHandler(tornado.web.RequestHandler):
    def get(self):
        self.write("Hello, world")

def make_app():
    return tornado.web.Application([(r"/", MainHandler),])

async def main():
    app = make_app()
    app.listen(8888)
    await asyncio.Event().wait()

if __name__ == "__main__":
    asyncio.run(main())