Everything I Use in Chrome DevTools for API Testing

Chrome ships with everything you need to test REST APIs without installing a separate client. Full disclosure: I built json-formatter-pro as part of Zovo, a collection of 16 Chrome extensions I maintain. Take my perspective accordingly. I test APIs in DevTools dozens of times a day, and the tight integration with your page's JavaScript context means you test against live cookies, tokens, and session state without copy-pasting anything. This post covers the native methods I actually use daily, from a first fetch() call to response mocking and performance profiling. Last verified: March 2026 , All steps tested on Chrome 134 (latest stable). Extension data verified against Chrome Web Store. The Ultimate Chrome JSON Extension , dcode How Chrome Handles API Requests When your JavaScript calls fetch() , the request starts in the renderer process, crosses an IPC boundary into the Network Service (a dedicated process since Chrome 67), and hits the OS network stack. The Network Service handles