Surge for Mac - Advanced Web Debugging Proxy for Mac & iOS
ModSecurity - ModSecurity is an Open Source web application firewall developed by Trustwave's SpiderLabs.
Weer - A HTTP protocol debugger with Chrome DevTools frontend interface
Shadow Daemon - Shadow Daemon is a collection of tools to detect, record and prevent attacks on web applications.
Charles Proxy - HTTP proxy / HTTP monitor / Reverse Proxy
ironbee - Universal web application firewall engine