Checks whether a value you did not fetch yourself is actually on the page it came from. Independently re-fetches the source and returns a signed pass/fail/unverifiable verdict. A claim is never certified unless the re-fetched page contains it, and anything unconfirmed is unverifiable, never pass. Server-rendered pages only. $0.01 per check. First 100 checks per client are free: resend this exact request with header X-Use-Free-Allowance: yes and no payment to use them.

PRESENCE tier (deterministic, no LLM): confirms the claimed value appears on the live page — it does NOT confirm the value is the right answer to the question. Positive verdict is "present", never "pass"; check_type web_field_presence_v1. For full verification use /verify. First 100 checks per client are free: resend with header X-Use-Free-Allowance: yes and no payment to use them.