I also have a version of the code that works on the first party server end. My service is third party like an ad widget.
Any thought's on how to add a captcha to Flatforum? I might be able to figure it out in my own time, but that might be a while.
My program works a lot like other captchas and can even be combined with them. You may use Google captcha alongside my FaucetSecurity for double security. I have even had up to three or four captchas at once in the past. With bitcoin faucet's it's necessary to defeat bots.
Here's another one of my site's that uses FaucetSecurity and handles a daily volume of traffic. http://autosurf247.com/
I created that site as an experiment in php and a personal goal, but also to demonstrate my captcha security in a setting that is often affected by bots.