CATS is an IDE for TypeScript and Web developers. CATS is open source software released under the Apache 2.0 license and runs on Linux, Windows and OS X. CATS itself is also written in TypeScript, so you can easily customize it to your needs if required. Although still new features are being added, CATS is already very usable and has built-in support for the following: Intelligent code editor and code completion for TypeScript sources. Syntax highlighting for over 110 languages (TextMate/Sublime Text.tmlanguage files can be imported). Support for code snippets. Support for refactoring and smart navigation. Very fast TypeScript compilation to JavaScript. Validation of the source code while you are typing. Editing features like folding, indentation and code formatting. Running your application from within IDE and using the WebKit debugger to debug. Flexible build system with support for external build systems like Grunt, Jake, Gulp and Makefiles. CATS supports the latest versions of TypeScript, so you are able to use all the new features.