- Compatible XF 1.x versions
- Additional requirements
- Visible branding
The captcha is embeded in an HTML form, runs client side in the user's browser and generates a token. The token is submitted together with the other form data. You can then validate this token on your server through our HTTP API.
Demo video showing the proof of work captcha
Unlike with a conventional captcha however, the user does not have to “proof they're human”. Instead, the captcha is a “proof of work” – making it uneconomic for spammers to game your system.
If the user gives consent, an opt-in token is stored in a cookie on your website. If this token is not expired, the miner can start again without a further explicit opt-in.
To prevent misuse, the text in the opt-in screen can not be altered. We will offer translations of this screen for different languages in the future.