Firefox Developer Tools Alternatives [Page 3]

Test your JavaScript, CSS, HTML or CoffeeScript online with JSFiddle code editor.

HTTP Header Checker Tools

Open Source free

Flagsmith lets you manage feature flags and remote config across web, mobile and server side applications. Deliver true Continuous Integration. Get builds out faster. Control who has access to new features. We're Open Source.

Try for free Open Source freemium

Muir is a mobile browser testing app without all the strings of cloud based suites.

Burp Suite is an integrated platform for performing security testing of web applications.

Plunker is an online community for creating, collaborating on and sharing your web development ideas.

HTTP Headers allows you to quickly see the HTTP header information for the current URL.

tcpdump is a common packet analyzer that runs under the command line.

Open Source

Compileonline is now renamed to Coding Ground

Built for those who build the Web. The only browser made for developers.

WPMU offers WordPress Plugins, WordPress Themes, WordPress Multisite and BuddyPress Plugins and Themes.

Smart Header is a browser extension that lets you manipulate the HTTP request headers and response header automatically.

Pastebin.com is a website where you can store text for a certain period of time.

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.

Open Source freemium €7.0 / Monthly (for a Pro subscription)