Arecibo is available as an open source library that you can install and try for free.
The client implementations are varied and will depend completely upon your site. There are some standard implementations available for Python, PHP and some frameworks.
The main server implementation developed by ClearWind uses Google App Engine as the server. To use Arecibo, just get a copy of the source and upload to your own App Engine instance.
Contributions are more than welcome to the main branch. At the moment all commits go through ClearWind, but we hope soon to set up a proper contribution agreement. For moment fork on github and send us the pull request.
