Sentry JavaScript Error Monitoring - Sentry JavaScript Error Monitoring is a user-friendly tool that is created to automatically apply source maps to transform minified, compiled code back to its original form.
Fiddler - Fiddler is a debugging program for websites.
Proxyman.io - Proxyman is a high-performance macOS app, which enables developers to view HTTP/HTTPS requests from apps and domains.
Fluxguard - Deployment, Defacement, & Security Monitoring
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.
Inspect Element - Inspect Element is a multi-functional tool that is introduced to get information about what makes the web tick, figure out what is broken in your sites, and mock-up what a specific color or font change would look like.