Is there a way that you can get a Portable/Online  Arduino IDE?
The standard IDE is portable as it runs as a stand-alone Java application. As such it requires no "installation" so to speak, and projects exist. So if you have it on rewritable media (e.g. a USB flash drive) and you store your projects on that same media, you in effect have a portable IDE. It will (I'm pretty sure) however, keep all it's build artifacts in temporary folders under the current users HOME directory.