captcha.cc
Documentation

Shared Clearance

Let captcha.cc reuse a recent real solve across sites that explicitly opt in.

how it works

  1. User solves a real captcha on any site.
  2. captcha.cc sets a short-lived clearance cookie on the captcha.cc domain.
  3. A later POST /v1/challenges request from another site can reuse that clearance if the site has accept_shared_clearance enabled.
  4. captcha.cc skips the image challenge and returns a fresh site-specific proof token.
  5. Your backend still decides whether to accept that proof for the current route or action.

site setting

This is off by default. A site must explicitly enable accept_shared_clearance.

backend decision

/v1/siteverify returns metadata.solve_mode as either interactive or shared_clearance. Use that to decide whether a given page or action should accept the proof.

browser requirement

Browser calls to captcha.cc must include credentials so the clearance cookie can be sent back on later requests.