Easy to add, advanced security
reCAPTCHA is a free service that protects your site from spam and abuse. It uses advanced risk analysis techniques to tell humans and bots apart.
Powered by machine learning
Hundreds of millions of CAPTCHAs are solved by people every day. reCAPTCHA makes positive use of this human effort by channeling the time spent solving CAPTCHAs into digitizing text, annotating images, building machine learning datasets. This in turn helps preserve books, improve maps, and solve hard AI problems.