reCAPTCHA
PHP client library for reCAPTCHA, a free service
..., or other verification step. Site owners register keys, embed a small client script, and verify tokens on the server to protect actions like sign-ups, logins, and form submissions. The ecosystem supports mobile and enterprise variants, but the repo focuses on common web integrations and best practices for verifying the token securely. Deployed correctly, reCAPTCHA reduces credential stuffing, bot sign-ups, and scraping without degrading the experience for typical users.