Custom Style Script
Disable cookies for current domain.
Right Click Validator
Right click on any webpage to validate it using the W3 NUValidator service.
Firebug Lite for Opera 15+
Live HTTP Headers
Monitor all HTTP/HTTPs traffic from your browser.
PDF API HTML5
ChroPath for Opera
AutonomIQ offers a developers platform ChroPath to generate and validate unique selectors like relative xpath with iframe support
Click on any HTML element to get the font info in a popup
This extension allows you to add your own custom website specific CSS style sheets.
Use Redux DevTools in the DevTools
SEO Analysis with Seoptimer
Just one click to SEO Analysis with Seoptimer
Website Color Changer
Extends the Developer Tools, adding a sidebar for colors manipulation
Edit the Page
Toggles the 'Design Mode' so that you can edit the contents of the page.
Quickly view the HTTP headers of the current tab.
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 predicts rating changes for Codeforces. It shows approximate deltas during and after the contest.
Browse JSON like you do it in Finder.
Shows the response times and uptime of a desired server. Useful to see how performs internet or a wireless access point.
Google Analytics Debugger
A browser extension for debugging Google Analytics tracking code
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, ...
Flag & WHOIS SEO Domain Full Info
Return the domain's IP address , information about security, localization of server, ping, etc.
This will take the URL of the current tab and send it to PageSpeed Insights for a web performance analysis.
View all HTTP Requests and Responses sent between the Web browser and the Web server.
Web Developer Checklist
Analyses any web page for violations of best practices
Get Thumbnails or Image to video YouTube
Make thumbnail previews or images from YouTube videos
Remove cookie(s) for the current domain
Remove cookie(s) for the current site with just one click
Website Analysis & SEO Tool
Website SEO audit tool that provides website analysis in SEO, performance, validity, security, accessibility and other criteria.
Picture in Play
Indicates whether the `picture` element is in use on a page.
Edit with Adobe Photoshop
Adds a context menu item to send image links directly to Adobe Photoshop photo editor