Custom Style Script
Browse JSON like you do it in Finder.
Disable cookies for current domain.
Modify request and response headers
GitHub on steroids
PDF API HTML5
Modify Header Value
Add, modify or remove a header for any request on desired domains.
Firebug Lite for Opera 15+
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, ...
Google Analytics Debugger
A browser extension for debugging Google Analytics tracking code
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.
WordPress Theme and Plugins Detector
This tool detects theme and plugins used on WordPress sites and displays information about them.
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.
This extension allows you to add your own custom website specific CSS style sheets.
Website Color Changer
Extends the Developer Tools, adding a sidebar for colors manipulation
Right Click Validator
Right click on any webpage to validate it using the W3 NUValidator service.
Shows the response times and uptime of a desired server. Useful to see how performs internet or a wireless access point.
Website Analysis & SEO Tool
Website SEO audit tool that provides website analysis in SEO, performance, validity, security, accessibility and other criteria.
Edit with Adobe Photoshop
Adds a context menu item to send image links directly to Adobe Photoshop photo editor
ChroPath for Opera
AutonomIQ offers a developers platform ChroPath to generate and validate unique selectors like relative xpath with iframe support
Quickly view the HTTP headers of the current tab.
OCR - Image Reader
A powerful optical character recognition (OCR) extension to capture and convert images to text
The tool to overlap your website layout with a grid.
Wayback machine website
Online service that have 452 billion web pages saved over time and who is domain tool in context menu
Get Thumbnails or Image to video YouTube
Make thumbnail previews or images from YouTube videos