Tampermonkey is the world's most popular userscript manager.
React Developer Tools is a tool that allows you to inspect a React tree, including the component hierarchy, props, state, and more. To get started, just open the Firefox devtools and switch to the "⚛️ Components" or "⚛️ Profiler" tab.
FireShot makes full page screen captures - http://bit.ly/RlBQMV Screenshots are quickly captured and: ― Saved as Image / PDF with links and text ― Sent to clipboard ― Printed Capture all open tabs or provide a list of the URLs for grabbing
Advanced Eyedropper, Color Picker, Gradient Generator and other colorful goodies...
Identify technologies on websites
The Web Developer extension adds various web developer tools to the browser.
Windscribe helps you circumvent censorship, block ads, beacons and trackers on websites you use every day.
DevTools extension for debugging Vue.js applications.
Userscript support for browsers, open source.
Cookie-Editor lets you efficiently create, edit and delete a cookie for the current tab. Perfect for developing, quickly testing or even manually managing your cookies for your privacy.