Twisted - Networking Engine in Python

Twisted is an event-driven networking engine written in Python. Twisted makes it easy to implement custom network applications, both servers and clients. It also supports many common network protocols, including SMTP, POP3, IMAP, SSHv2, DNS and lot more. The twisted.web webserver is a scalable, small-footprint web server that's easy to configure. It's efficient enough to serve a high-traffic website.