HTTP(S) Debugging Proxy, Analyzer & Client
"HTTP Toolkit offers beautiful and open-source tools to debug, test and develop with HTTP(S).
HTTP Toolkit is built using React.js. The main website is a static React site, built using Gatsby and deployed on Netlify and the app itself is an Electron wrapper around a large React.js + Mobx application.
The app includes a high-performance infinite feed of live HTTP traffic as it's collected, a full syntax-highlighted editor for languages from CSS to XML with autoformatting, and lots of other neat React tricks."