FCaptcha guards your forms with an invisible check that spots bots, headless browsers, and AI agents steering real browsers, all from a server you run yourself. Drop the widget into a signup or contact form and it quietly watches how the visitor actually behaves: pointer movement, typing cadence, scroll shape, and dozens of other signals that separate a person from a script. Vision agents that screenshot and click, and computer-use agents driving a browser through automation protocols, leave input traces the scoring engine catches. Self-declaring crawlers get flagged by name, and signed agent requests are verified cryptographically so polite, identified bots can be allowed while anonymous automation is blocked. A proof-of-work challenge adds a liveness gate behind the scenes. Humans see no puzzle at all, in any of 34 languages, and the widget meets accessibility standards for screen-reader and keyboard-only visitors. Your backend verifies each token through the same siteverify contract that Turnstile, reCAPTCHA, and hCaptcha use, so switching providers is a change of address rather than a rewrite. No cookies are set, no visitor data travels to a third party, and nothing phones home. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.