A firefox addon allowing the user to enable CORS everywhere by altering http responses.
Report issues to the repository, with enough information to reproduce the problem:
https://github.com/spenibus/cors-everywhere-firefox-addon/issues
A tool for viewing SAML and WS-Federation messages sent through the browser during single sign-on and single logout.
An easy-to-use font inspector to get CSS styles of the selected element
Allows URI texts written in webpages to be loaded by double clicks.
Delete browsing data directly from the browser toolbar. Clear cookies, history and cache with a single click.
Accelerate your SEO efforts on the fly. SEOquake is a free plugin for browsers that provides you with key SEO metrics for a specific page, along with other useful tools such as SEO Audit and many others.
A REST client for the rest of us
Fast JSON viewer - highlights, shows items count/size, handles large files
Toggle JavaScript engine on and off the easy way
Easily add (Access-Control-Allow-Origin: *) rule to the response header.
Cache clearing made easy. One click.
A reference for the codes to generate Emojis on popular sites like GitHub or Basecamp and Unicode characters for Twitter and Facebook.
Search Emojis by name or view recently selected items. Emojis are automatically copied to the clipboard.
Exports all cookies to a Netscape HTTP Cookie File, as used by curl, wget, and youtube-dl, among others.
Manage browser's requests, include modify the request headers and response headers, redirect requests, cancel requests
Displays the HTTP header. Edit it and send it.
add javascript that will run on this domain.
back up your scripts in the options area (shortcut there by clicking the "JS" letters in the bottom right)
window.crypto.signText replacement plus enhancements
A free extension of the web tool https://coolsymbol.com/emojis/emoji-for-copy-and-paste.html. It helps input emoji in the web browser with an extensive search functionality.
A HackBar for new firefox (Firefox Quantum). This addon is written in webextension and alternatives to the XUL version of original Hackbar.
Press F12 to use HackBar
A REST client for almost any web service.
Discover what runs a website - This Firefox extension helps you identify technologies used on any website at the click of a button.
manage, edit, manipulate, plot and save one or multiple SQLite databases simultaneously
Add, modify or remove a header for any request on desired domains.
HTML Validator is a Mozilla extension that adds HTML validation inside Firefox, Mozilla. The number of errors of a HTML page is seen on the form of an icon
For Firefox 56, use 0.974 (see all versions below).
For Firefox 57, see Web Extensions.
My IP Hider VPN is number one tool for hiding your IP and unblocking any web site! If your Firefox version is less then 55 please install older My IP Hider VPN from "Version History" (https://goo.gl/7ZQQjZ)
Allows all sites to be loaded in iframes, despite X-Frame-Options header settings.
EditThisCookie is a cookie manager. You can add, delete, edit, search, protect and block cookies!
This extension allows you quickly to set the X-Forwarded-For HTTP Header
[No License, FOREVER FREE] A HackBar for new firefox (Firefox Quantum). This addon is written in webextension and alternatives to the XUL version of original Hackbar.
You can ask request here: https://github.com/Hack-Free/HackBar
Simple tool for measuring arbitrary parts of a page. Does not and will never contain adware.