Online IDEs have cut the number of tools you need tenfold – now, to access and edit your code, all you need is an internet connection. This allows you to access and edit your code from just about any computer worldwide, freeing you from the need to have constant access to a single computer where your files are stored.

Shiftedit

ShiftEdit is an online IDE for developing PHP, Ruby, HTML, CSS and JavaScript using (S)FTP, Dropbox or Google Drive. ShiftEdit is an online PHP, Ruby, Java, HTML, CSS and JavaScript editor with built-in (S)FTP and Dropbox. Ideal for web development.

CodeRun

CodeRun Studio is a cross-platform Integrated Development Environment (IDE), designed for the cloud. It enables you to easily develop, debug and deploy web applications using your browser.

Ideone: Web Based IDE and Debugging Tool

Ideone is a web application which enables you to execute and share code in about 40 programming languages. It’s like a pastebin for programmers to quickly run, debug and share code online, without having to install a desktop based IDE.

Cloud9 IDE

Write, run, and debug your code with our powerful and flexible cloud IDE. Collaborate on your workspaces publicly, or keep them private. The choice is yours!

jsfiddle

jsFiddle lets one easily test snippets of JavaScript/CSS/HTML code on-the-fly, adding optional libraries like jQuery.

Koding

Koding, a cloud development environment and collaboration platform, emerged from private beta today, allowing developers worldwide to request a login to begin coding in an entirely new way.

Akshell

Akshell is a platform for creating web apps in JavaScript right from a browser. It was designed to provide a desktop-like experience in a browser window. It doesn’t require installation or configuration; you can use it from anywhere without a hassle. And you even don’t have to sign up.

Tinkerbin

Tinkerbin lets you play around with HTML, JavaScript and CSS without creating files or uploading to servers.