Custom Style Script
GitHub code tree on steroids
Extension source viewer
View source code of extensions in the Chrome Web Store, Firefox or Opera addon gallery. Has button to install from Chrome Web Store.
Firebug Lite for Opera 15+
Disable cookies for current domain.
Browse JSON like you do it in Finder.
Right Click Validator
Right click on any webpage to validate it using the W3 NUValidator service.
PDF API HTML5
Click on any HTML element to get the font info in a popup
GitHub code tree on steroids
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, ...
This extension allows you to add your own custom website specific CSS style sheets.
View all HTTP Requests and Responses sent between the Web browser and the Web server.
Edit the Page
Toggles the 'Design Mode' so that you can edit the contents of the page.
Use Redux DevTools in the DevTools
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!
Open in GIMP photo editor
Adds a context menu item to send images directly to GIMP photo editor
Google Analytics Debugger
A browser extension for debugging Google Analytics tracking code
Flag & WHOIS SEO Domain Full Info
Return the domain's IP address , information about security, localization of server, ping, etc.
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
SEO Analysis with Seoptimer
Just one click to SEO Analysis with Seoptimer
Picture in Play
Indicates whether the `picture` element is in use on a page.
WordPress Theme and Plugins Detector
This tool detects theme and plugins used on WordPress sites and displays information about them.
Edit with Adobe Photoshop
Adds a context menu item to send image links directly to Adobe Photoshop photo editor
Remove cookie(s) for the current domain
Remove cookie(s) for the current site with just one click
Get Thumbnails or Image to video YouTube
Make thumbnail previews or images from YouTube videos
Internet users feedback about the sites
Web Developer Checklist
Analyses any web page for violations of best practices
This will take the URL of the current tab and send it to PageSpeed Insights for a web performance analysis.
Website Analysis & SEO Tool
Website SEO audit tool that provides website analysis in SEO, performance, validity, security, accessibility and other criteria.
This extension predicts rating changes for Codeforces. It shows approximate deltas during and after the contest.