BuiltWith Technology Profiler
Find out what the website you are visiting is built with using this extension.
Click on any HTML element to get the font info in a popup
PDF API HTML5
Browse JSON like you do it in Finder.
Firebug Lite for Opera 15+
GitHub on steroids
Disable cookies for current domain.
Modify Header Value
Add, modify or remove a header for any request on desired domains.
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, ...
Edit the Page
Toggles the 'Design Mode' so that you can edit the contents of the page.
Live HTTP Headers
Monitor all HTTP/HTTPs traffic from your browser.
This extension allows you to add your own custom website specific CSS style sheets.
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!
View all HTTP Requests and Responses sent between the Web browser and the Web server.
WordPress Theme and Plugins Detector
This tool detects theme and plugins used on WordPress sites and displays information about them.
Quickly view the HTTP headers of the current tab.
Flag & WHOIS SEO Domain Full Info
Return the domain's IP address , information about security, localization of server, ping, etc.
Website Color Changer
Extends the Developer Tools, adding a sidebar for colors manipulation
Edit with Adobe Photoshop
Adds a context menu item to send image links directly to Adobe Photoshop photo editor
Shows the response times and uptime of a desired server. Useful to see how performs internet or a wireless access point.
OCR - Image Reader
A powerful optical character recognition (OCR) extension to capture and convert images to text
Website Analysis & SEO Tool
Website SEO audit tool that provides website analysis in SEO, performance, validity, security, accessibility and other criteria.
ChroPath for Opera
AutonomIQ offers a developers platform ChroPath to generate and validate unique selectors like relative xpath with iframe support
Wayback machine website
Online service that have 452 billion web pages saved over time and who is domain tool in context menu
A small extension to validate the markup of current tab
Remove cookie(s) for the current domain
Remove cookie(s) for the current site with just one click
Right Click Validator
Right click on any webpage to validate it using the W3 NUValidator service.