Community driven list of useful things for front end developers. How to contribute?

• Opera
• Mozilla
• Chromium
• Webkit

• Opera Mini, Opera Mobile
• iOS Simulator in XCode

• Chrome Canary
• IE 10
• Opera Next Beta, Opera Next Labs, Opera Next Nightly
• Webkit Nightly
• Firefox Nightly, Firefox Aurora

• Firefox:
  • Official archive
  • Bash script
  • All Firefox Releases
• Opera:
  • Official archive
  • Version history
• Safari

• Chrome Dev HTTP Client
• Firebug
• Web Developer for Firefox

• Dabblet
• JSBin
• gist.github
• JSFiddle
• CodePen
• refiddle
• RegExr
• CSS-Tricks snippets

• PNG compressor
• Tiny png - can make IE6 friendly PNGs
• IMGO
• JPEG compressor
• placehold.it
• lorempixel
• Sprite generator
• Favicon generator

• [XML to JSON](XML to JSON http:https://jsontoxml.utilities-online.info)
• MicroJS
• JavaScript Beautifier
• JavaScript Patterns Collection
• Easing animation tool
• Cubic-Bezier
• Easings function

• html5please
• mobilehtml5

• Data URL Toolkit, online service
• css3please
• The CSS3 Test
• CSScomb
• Procssor: CSS Beautifier
• Eric Meyer's reset
• normalize.css
• CSS Gradient finder
• CSS Gradient generator
• Sprite Cow - CSS Sprites
• CSS3 Transitions, Transforms and Animation Tutorial

• Less
• SASS and SCSS
• xCSS - PHP based CSS preprocessor
• Stylus
• Compass
• CSS to SASS
• CSS to Less

• Twitter bootstrap
• Blueprint CSS
• HTML5 boilerplate - The web’s most popular front-end template
• HTML5 mobile boilerplate - A best practice baseline for your mobile web app
• 960gs - CSS grids system framework

• Github style guide
• Google style guides
• SMACSS - Scalable and Modular Architecture for CSS
• OOCSS - Object oriented CSS
• BEM - Block Element Modificator

• caniuse
• The Toolbox
• humans.txt
• robots.txt
• Adobe Shadow
• Unicode Emoticons
• Special Characters Easy to Paste
• Entity Conversion Calculator
• ipsum.me
• Schema.org - Most modern microformat documentation supported by Google, Bing, Yandex and Yahoo
• Microformats.org - hcard, hcalendar and etc.
• base64 converter

• StatCounter
• LiveInternet
• OpenStat

• YUI JS, CSS compressor
• CSSO - Cleaver css optimizer
• YSlow - Cross-browser plugin for page speed and performance testing
• Google page speed - Page speed measurement tools collection from Google
• Web page test - Check page speed from multiple locations around the globe using real browsers
• jsPerf — JavaScript performance playground

• Google CDN
• Yandex CDN
• cdnjs

• jQuery Docs
• MDN

• W3C HTML Validator
• W3C CSS Validator
• CSSLint
• JSLint
• JSHint
• CSS Lint

• CSSFontStack
• Font Squirrel
• Google WebFonts
• Fontello — iconic fonts scissors
• Online Font Converter
• Check font name by screenshot

• ColorSnapper
• Gitbox
• LiveReload
• PixFit
• xScope
• MAMP PRO
• DataURLMaker
• ImageOptim
• BLESS CSS - Fighting IEs CSS selectors limit, and nice tool for checking CSS selectors count

• GitHowTo
• Pro Git