PDF API HTML5
Modify Header Value
Add, modify or remove a header for any request on desired domains.
GitHub on steroids
Firebug Lite for Opera 15+
Use Redux DevTools in the DevTools
Live HTTP Headers
Monitor all HTTP/HTTPs traffic from your browser.
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!
Right Click Validator
Right click on any webpage to validate it using the W3 NUValidator service.
Click on any HTML element to get the font info in a popup
ChroPath for Opera
AutonomIQ offers a developers platform ChroPath to generate and validate unique selectors like relative xpath with iframe support
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, ...
Browse JSON like you do it in Finder.
Edit the Page
Toggles the 'Design Mode' so that you can edit the contents of the page.
View all HTTP Requests and Responses sent between the Web browser and the Web server.
Picture in Play
Indicates whether the `picture` element is in use on a page.
This extension allows you to add your own custom website specific CSS style sheets.
SEO Analysis with Seoptimer
Just one click to SEO Analysis with Seoptimer
This will take the URL of the current tab and send it to PageSpeed Insights for a web performance analysis.
WordPress Theme and Plugins Detector
This tool detects theme and plugins used on WordPress sites and displays information about them.
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
Get Thumbnails or Image to video YouTube
Make thumbnail previews or images from YouTube videos
Google Analytics Debugger
A browser extension for debugging Google Analytics tracking code
Website Color Changer
Extends the Developer Tools, adding a sidebar for colors manipulation
Quickly view the HTTP headers of the current tab.
Open in GIMP photo editor
Adds a context menu item to send images directly to GIMP photo editor
Web Developer Checklist
Analyses any web page for violations of best practices
The simplest extension for working with web fonts
Shows the response times and uptime of a desired server. Useful to see how performs internet or a wireless access point.
Edit with Adobe Photoshop
Adds a context menu item to send image links directly to Adobe Photoshop photo editor
OCR - Image Reader
A powerful optical character recognition (OCR) extension to capture and convert images to text