[mortov]

Alas, using the latest Firefox 29 (downloaded yesterday) all I get in response to 'Try Now' is :

Loading Codio, hold tight... Browser not supported!

Your browser is very old and will not work correctly with Codio. Please upgrade to the latest version or use a modern browser

[grageth]

Make sure you don't have settings or extensions (from previous installs perhaps) that are changing your user agent. I personally don't like sites checking user agents. I say give me what you got and let me decide of my browser is supported or not.

[joelmoss]

That is very strange, because I also use Firefox 29, and all works fine for me. What OS are you on?

[KhalPanda]

Working fine for me, Ubuntu 14.04 / Firefox 29.