Eclipse Orion!

Brackets is an open-source editor for web design and development built on top of web technologies such as HTML, CSS and JavaScript. The project was created and is maintained by Adobe, and is released under an MIT License.

Cloud9 is a code editor and development environment built with browser technology yet with the power of a desktop IDE. It's available both as an online service and as a locally hosted platform.

Codeanywhere is a code editor in a browser with a powerful ftp client integrated, and all popular web formats are supported (HTML, PHP, JavaScript, CSS, and XML).

Codiad is an open source, web-based, cloud IDE and code editor with minimal footprint and requirements

Koding is a developer community and cloud development environment where developers come together and code in the browser – with a real development server to run their code. Developers can work, collaborate, write and run apps without jumping through hoops and spending unnecessary money. The Cloud Development Environment

kodeWeave is a realtime coding playground for HTML, CSS and Javascript. Similar to JSFiddle and JSBin, but kodeWeave was made to work offline but also as a prototyping application to build applications for desktop operating systems while on mobile devices. (PhoneGap Build is recommended for mobile devices)

ICEcoder is a browser code editor which provides a modern approach to building websites. By allowing you to code directly within the web browser, online or offline, it means you only need one program (your browser) to develop sites, plus can test on actual web servers. After development, you can also maintain the website easily, all of which make for speedy and smart development.

Eclipse Che is an open source project under the Eclipse top-level project. It's named after Cherkasy Ukraine, the city where development started.

Codenvy let's developers contribute to a project in seconds without installing software. Modify, run and debug code in the cloud or on-prem with no software to install.

sourceLair is a cloud based software development environment aiming to revolutionize its market by letting developers work everywhere, with the most reliable, efficient and elegant development environment available.