Squid redirector written in python implements a dynamic whitelisting scheme. Users add new websites to the whitelist via a webform, which is user-friendly and sysadmin-friendly, but mitigates compromise and data exfiltration over the web.
This has a Python ICAP (Internet Content Adaptation Protocol) server and IRML parser. Using this, a web proxy can do rule-based adaptation of content before delivery to clients. Has a Python proxylet API and squid-icap-client code too.