mitmproxy/doc-src/scripting/libmproxy.html

All of mitmproxy's basic functionality is exposed through the __libmproxy__
library. The example below shows a simple implementation of the "sticky cookie"
functionality included in the interactive mitmproxy program. Traffic is
monitored for __cookie__ and __set-cookie__ headers, and requests are rewritten
to include a previously seen cookie if they don't already have one. In effect,
this lets you log in to a site using your browser, and then make subsequent
requests using a tool like __curl__, which will then seem to be part of the
authenticated session.

$!example("examples/stickycookies")!$