The furnace.recaptcha vocabulary implements support for the recaptcha. Recaptcha is a web service that provides the user with a captcha, a test that is easy to solve by visual inspection, but hard to solve by writing a computer program. Use a captcha to protect forms from abusive users.

The recaptcha responder is a filter-responder that wraps another responder. Set the domain, public-key, and private-key slots of this responder to your recaptcha account information.

Wrapping a responder with recaptcha support:

<recaptcha> ( responder -- recaptcha )

Validating recaptcha:

validate-recaptcha ( -- )

Symbol set after validation:

recaptcha-error

An example:
Recaptcha example