Except it's actually worse than typical frontends. It's maybe cleaner looking, but it doesn't allow you to test all font types at the same time.

http://www.network-science.de/ascii/ This one exists since 1996 and allows all fonts to be rendered. Option is very far on to top of font selection drop—down.

Edit: that to this

This!

I did my own take on this that addresses both of your concerns: 1. Update as you type 2. Show all fonts

http://ascii.today/

This incurs performance issues in long strings, but works great for most uses.

This is really fantastic work. Bookmarking for later.

It amazes me that FIGlet are still releasing for MS-DOS, Acorn, OS/2 and Amiga in 2014.

Are there any that are client-side / javascript instead of server side?

If you like figlet, pipe its ouput into lolcat

Or pipe to sed for "emoji art"