What does it do?
Twisted is a framework for writing networked programs that can juggle many connections at the same time without getting stuck waiting on any single slow one, using an approach called asynchronous programming. Imagine a single incredibly efficient waiter serving fifty tables by never standing idle at any one table waiting for food to cook, instead checking in on whichever table needs attention next; that’s roughly how Twisted lets one program handle thousands of network connections without needing thousands of separate workers. It provides building blocks for practically any networking task, web servers, chat systems, email handling, custom protocols, all built around this same non-blocking style. This approach existed in Twisted years before Python added its own native asyncio tools for similar patterns.
See it in action
This starts a small always-on server that repeats back to a visitor exactly whatever data they send it, and keeps running to serve more connections.
from twisted.internet import protocol, reactor
class Echo(protocol.Protocol):
def dataReceived(self, data):
self.transport.write(data)
class EchoFactory(protocol.Factory):
def buildProtocol(self, addr):
return Echo()
reactor.listenTCP(8000, EchoFactory())
reactor.run()Why would a non-developer care?
The general technique Twisted pioneered in Python, handling huge numbers of simultaneous connections efficiently, is exactly what modern chat apps, live-updating websites, and streaming services rely on at scale. Twisted was doing this in Python well before it became a mainstream, widely-taught approach.
Real-world examples
Twisted has been around since 2002, considerably predating Python’s built-in asyncio library, and it directly influenced how Python eventually added native support for this style of programming. It also quietly powers Scrapy, one of the most widely used Python web scraping frameworks, which relies on Twisted’s networking engine to fetch many web pages simultaneously and efficiently.
Who uses it
Developers building high-performance networked applications and infrastructure tools that need to manage large numbers of simultaneous connections efficiently.
How it compares to alternatives
Python’s own asyncio, added natively to the language in 2014, was heavily inspired by ideas Twisted had already been using for over a decade, and many newer projects now reach for asyncio directly, though Twisted remains mature, stable, and still actively used, especially in existing large codebases.
Fun fact
Twisted was created by Glyph Lefkowitz, and its ideas around asynchronous, event-driven programming shaped the design conversations that eventually led to Python adding asyncio to its standard library.