BuiltWith Technology Profiler
Find out what the website you are visiting is built with using this extension.
Corser - Authorize CORS requests
Cross-browser extension for authorizing cross-origin resource sharing (CORS) requests. This extension can be installed on browsers supporting the WebExtensions API (https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions) It intercepts all CORS requests and responses headers, and records/adds/changes their values so as to authorized unauthorized CORS requests. Use this extension only for testing purposes
Firebug Lite for Opera 15+
PDF API HTML5
GitHub code tree on steroids
Use Redux DevTools in the DevTools
Live HTTP Headers
Monitor all HTTP/HTTPs traffic from your browser.
Browse JSON like you do it in Finder.
Browserling - Cross-browser testing
Cross-browser test websites in the most popular browsers such as Internet Explorer, Edge, Chrome, Firefox, Safari and Opera. Try for free!
This extension allows you to add your own custom website specific CSS style sheets.
Click on any HTML element to get the font info in a popup
Picture in Play
Indicates whether the `picture` element is in use on a page.
Live editor for CSS and LESS - Magic CSS
Live preview of CSS/LESS code with an in-page editor. Autocomplete, convert LESS to CSS, beautify, minify, CSS reloader, linter, ...
ChroPath for Opera
AutonomIQ offers a developers platform ChroPath to generate and validate unique selectors like relative xpath with iframe support
View all HTTP Requests and Responses sent between the Web browser and the Web server.
Quickly view the HTTP headers of the current tab.
Edit the Page
Toggles the 'Design Mode' so that you can edit the contents of the page.
The simplest extension for working with web fonts
Website Color Changer
Extends the Developer Tools, adding a sidebar for colors manipulation
Google Analytics Debugger
A browser extension for debugging Google Analytics tracking code
Open in GIMP photo editor
Adds a context menu item to send images directly to GIMP photo editor
Website Analysis & SEO Tool
Website SEO audit tool that provides website analysis in SEO, performance, validity, security, accessibility and other criteria.
An extention to show/inspect and analyze fonts in web-pages.
Block Yourself from Analytics
Block your Google Analytics™ activity for the websites you own, no more false stats.
Flag & WHOIS SEO Domain Full Info
Return the domain's IP address , information about security, localization of server, ping, etc.
Shows the response times and uptime of a desired server. Useful to see how performs internet or a wireless access point.
SEO Analysis with Seoptimer
Just one click to SEO Analysis with Seoptimer
A browser extension that brings a new GitHub experience
Edit with Adobe Photoshop
Adds a context menu item to send image links directly to Adobe Photoshop photo editor