Squid Proxy - Website Content Acceleration and Distribution. Thousands of web-sites around the Internet use Squid to drastically increase their content delivery. Squid can reduce your server load and improve delivery speeds to clients.
Surge for Mac - Advanced Web Debugging Proxy for Mac & iOS
CCProxy - Want to share Internet connection? Get every computer online through a single Internet connection?
Charles Proxy - HTTP proxy / HTTP monitor / Reverse Proxy
Apache Traffic Server - Fast, scalable and extensible HTTP/S 2 and 1.1 compliant caching proxy server.
HTTP Headers - HTTP Headers allows you to quickly see the HTTP header information for the current URL.