Free web-based UI design tools

Junior WebHelper Joined: 01 Apr 2011 Posts: 4

For some of my own work, I'm looking for a web-based UI prototyping tool, so I can log in from anywhere and work on UI sketches. I'd expect this to be Flash or Javascript based, and not require any special browser plugins.

I can find loads of commercial products, but for my free/volunteer project work these are not sustainable (out of interest, I've had a quick read-up on Balsamiq, Pidoco, Creately, Mockingbird, Mockflow and plenty of others). For free, I've found FluidIA, which looks in an early stage of development, and Pencil, which breaks my rule about not requiring plugins.

If anyone would like to share how they do UI design in a way that makes sketches quick to make and easy to share, I'd be interested to see what you do.

Incidentally, there is quite a good wireframing resource here, which I've used to look up some of the above tools.