Fiddler - Fiddler is a debugging program for websites.
HTTP Toolkit - Beautiful, cross-platform & open-source tools to debug, test & build with HTTP(S). One-click setup for browsers, servers, Android, CLI tools, scripts and more.
Proxyman.io - Proxyman is a high-performance macOS app, which enables developers to view HTTP/HTTPS requests from apps and domains.
DebugBear - Track site speed and Core Web Vitals
Surge for Mac - Advanced Web Debugging Proxy for Mac & iOS
Embeddable - Build Remarkable Analytics Experiences. The toolkit for building fast, interactive, fully-custom analytics experiences into your app.