Hello, SirFizX here. This is a fork of an open source project by @programmerhat. You can check it out the original project on Github: programmerhat/vim-online-editor . The source for this fork can be found on Github: EricEisaman/vim.
If you happen to be new to Vim, here is a playlist of videos to get you started.
Got a feature request? I'd love to hear it! I'm on Twitter @SirFizX207.
If you've got your own vimrc, you'll probably want to install that straight away. Click on "Load vimrc", then copy your vimrc, and click "Paste" to install your vimrc. Do ":write" and reload the tab. The vimrc will be installed.
Caveat is that this app currently does not support plugins.
Then just click the vim box and you're good to go!
It's free. Doesn't cost anything.