Charles Proxy - HTTP proxy / HTTP monitor / Reverse Proxy
Coverity Scan - Find and fix defects in your Java, C/C++ or C# open source project for free
Proxyman.io - Proxyman is a high-performance macOS app, which enables developers to view HTTP/HTTPS requests from apps and domains.
SonarQube - SonarQube, a core component of the Sonar solution, is an open source, self-managed tool that systematically helps developers and organizations deliver Clean Code.
Postman - The Collaboration Platform for API Development
Embold.io - Peer Code Review