Hunchentoot is a web server written in Common Lisp and at the same time
a toolkit for building dynamic websites. As a stand-alone web server,
Hunchentoot is capable of HTTP/1.1 chunking (both directions),
persistent connections (keep-alive), and SSL.

Hunchentoot provides facilities like automatic session handling (with
and without cookies), logging, customizable error handling, and easy
access to GET and POST parameters sent by the client. It does not
include functionality to programmatically generate HTML output. For this
task you can use any library you like, e.g. (shameless self-plug) CL-WHO
or HTML-TEMPLATE.

Hunchentoot talks with its front-end or with the client over TCP/IP
sockets and optionally uses multiprocessing to handle several requests
at the same time. Therefore, it cannot be implemented completely in
portable Common Lisp. It currently works "natively" with LispWorks
(which is the main development and testing platform), and additionally
on all Lisps which are supported by the compatibility layers usocket and
Bordeaux Threads.

Hunchentoot comes with a BSD-style license so you can basically do with
it whatever you want.

Hunchentoot is for example used by Trip Planner, clutu, TwitterBuzz,
Jalat, Heike Stephan, xOs, and the NIST.