CodeKit helps you build websites faster and better. Its flagship features are listed below and the one-minute teaser video to the right is a good place to start. 

Compile Everything
Process Less, Sass, Stylus, Jade, Haml, CoffeeScript, Javascript and Compass files automatically each time you save. Easily set options for each language.

Live Browser Reloads
Instantly see changes in your browser, with animation and without hitting the refresh button or installing plugins. Great for tweaking layouts!

Combine & Minify
Reduce load times by mashing Javascript & CoffeeScript files together and then minifying with Uglify.js. It's so easy, you'll giggle like a schoolgirl. Seriously.

Optimize Images
Losslessly reduce JPEG and PNG file sizes with one click and see the savings. One less thing to do at deployment. (More compression options coming soon!)

JSHint & JSLint
Makes debugging scripts fun and easy. Instantly find that one hanging comma that kills IE, or enforce coding styles and best practices across teams.

Team Collaboration
Sync project settings across teams and computers in an open JSON format. Keep everyone on the same page or easily jumpstart new sites.

Easy Frameworks
Keep just one copy of a file on your drive and easily use it across many projects without worrying about file paths. No more copying files into every new site.

It Just Works
There's nothing to install or configure. No mucking around the command line. Just run the app and start working. It's that easy. 

REQS: Mac OS 10.7+

Version 1.2.3 (6554)
1 August 2012
ΓÇó Resolved several issues with Mountain Lion compatibility.
ΓÇó FIXED: an issue that produced crashes when checking a script with JSLint on 10.8. (This one wasn't my fault; there was an error in the JSLint library itself that crashed the new JavascriptCore engine in 10.8. Even Doug Crockford screws up, apparently.)
ΓÇó FIXED: @import paths that begin with a period to indicate the current directory will now link correctly in the app.
ΓÇó Killed an edge-case memory leak.
ΓÇó The file-watching engine (VDKQueue) is now *even* faster. You'd pretty much need an atomic clock to track it, though.
ΓÇó The status bar icon is now retina-fied. Mainly because some guy requested it on Twitter. His face will soon be introduced to a Retina Macbook Pro traveling at high velocity.
ΓÇó Node.js --> updated to 0.8.2 (brings full support for UTF-16)
ΓÇó Less.js --> still at version 1.3.0, but updated to a newer commit that brings support for keyframe animations in WebKit and ratios in media queries.
ΓÇó Uglify.js --> updated to 1.3.3
ΓÇó Stylus --> updated to 0.28.2
ΓÇó JSLint --> updated to the 27 July 2012 build.
ΓÇó JSHint --> updated to the 30 July 2012 build. (New "camelcase" and "worker" options)
ΓÇó Sass --> updated to 3.1.20. (Which is like 3.2, if you squint.)
ΓÇó Jade --> updated to 0.27.0. (Because TJ hates numbers larger than 1.)

Credits to Special [K]