Validity

Validity can be used to quickly validate your HTML documents from the address bar. Just click the icon in the address bar to validate the current document without leaving the page.
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Speed Tracer

Speed Tracer is a tool to help you identify and fix performance problems in your web applications. It visualizes metrics that are taken from low level instrumentation points inside of the browser and analyzes them as your application runs.
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Built With Technology Profiler

BuiltWith is a web site profiler tool. Upon looking up a page, BuiltWith returns all the technologies it can find on the page. BuiltWith’s goal is to help developers, researchers and designers find out what technologies pages are using which may help them to decide what technologies to implement themselves.
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SEO Site Tools

This tool is the most comprehensive SEO Tool on any browser… not only does it pull more metircs from more sources, including social media reactions, it also enhances common tools like Yahoo Site Explorer and Google Webmaster tools with links anchor text and pagerank.
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PHP Documentation

PHP documentation, the official PHP Manual for developers. Get your documentation on any PHP function right from your browser.
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Pendule

Pendule displays linked and embedded style sheets of the current page in a new tab.
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jQuery Shell

jQuery Shell allows you to run JavaScript and jQuery 1.4.2 commands in the context of the current web page. It is simple tool to use when experimenting with / learning JavaScript and jQuery commands.
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Firebug Lite

Firebug Lite is a tool for web developers, that allows you to edit, debug, and monitor CSS, HTML, and JavaScript live in any web page.
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Domain Availability Checker

This plugin checks a domains availability straight from your toolbar. A large amount of domain extensions and registrars are supported.
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Chrome Sniffer

This extension will help web developer to inspect web framework / CMS and javascript library running on current browsing website. An icon will appear on address bar indicates the detected framework.
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Chrome Editor

This extension allows you to code right within the browser. You also have the ability to save a code reference for later use. It saves it to your computer locally.
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Chrome SEO

The Google Chrome SEO Extension provides easy access to Search Engine Optimization Tools that can help you with Competitive Analysis, Keyword Research, Backlink Checks, PageRank Checks and other daily SEO tasks.
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Web Developer

The Web Developer extension adds a toolbar button to the browser with various web developer tools.
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Meta SEO Inspector

This extension is mainly aimed at web developers that need to verify the description tag of their site to follow the Webmasters’ Google Guidelines, SEO, or even to who is curious about page contents that are usually not visible, but can reveal interesting site properties.
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JavaScript Console

Allows you to do simple JS prototyping on any web page. Especially handy for development.
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Inline Code Finder

Finds HTML elements with inline JavaScripts events, inline styling and JavaScript links and when it finds them, it will highlight them.
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Practice HTML

You can use this Google Chrome Extension HTML board to practice new ideas, check the code for your web page or auction listing, or just to check a chat board post to make sure it looks the way you think it should.
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XML Tree

Displays XML data in a user friendly way.
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Regular Expression Checker

Simple regular expression checker/tester. A very user friendly and simple tool.
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jQuery Selectors

This extension can be used to apply a jQuery selector to any web page. This is suitable for new jQuery users who want to learn jQuery selectors.
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WebEdit

Can be used to edit any webpage. Just press F12 on any webpage, and edit text and delete things like photos and embed elements just for fun. (Changes are not permanent.)
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View Selection Source

It makes very easy to view the source of any selected element on a webpage.
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MultiSwitch

Whenever you have the need to simply switch between development, test and productive hosts you should use MultiSwitch.
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Live Editor

With this extension you can test every little bit of HTML/CSS code without refreshing the page.
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Session Buddy

Session Buddy is a flexible session manager extension for Google Chrome that allows you to quickly save and restore session tabs.
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Comment and suggest your favorite Chrome Extensions for Developers. You may want to check out the Complete Collection of Chrome Extensions for Designers. Don’t miss a post, subscribe to our RSS feed and follow us on Twitter.