# `POST /v1/liveness/check` — Passive liveness on one to three selfies

Passive presentation-attack detection: the hosted flow's two PAD models and its deepfake model on the images you send. Weaker than the hosted active liveness (no challenge, no screen flash, no capture binding): it catches printed photos, screens and masks the models know, not a replayed or injected stream. CHF 0.60 per answered call; refunded when it could not run. Needs the liveness:check scope.

Parameters:
- `Idempotency-Key` (header, string): Reuse on retries (printable non-space ASCII). For 24 hours the same key and the same request return the saved answer and check id without a second charge; a different request under the key returns 409.

Body:
- `deepfake` (boolean)
- `reference_id` (string): Your own id, echoed in the answer.
- `sandbox_outcome` (string): Sandbox keys only: which test answer to return. No model runs and nothing is charged. One of `live`, `spoof`, `review`, `no_face`.
- `images` (array of string, required): One to three images of one person (or a single `image` field).

Responses:
- 200: The answer.
- 400: Invalid input.
- 401: Missing, unknown or expired API key.
- 402: The balance does not cover the check.
- 403: The key lacks the product's scope, its IP allowlist refuses the caller, or (code production_not_allowed) the organization may not use production yet.
- 409: The Idempotency-Key is in progress (Retry-After: 1) or was used with a different request.
- 413: A file or the body is too large.
- 415: A file is not of an accepted type (checked by its bytes, not its name), or the body is neither multipart nor JSON.
- 422: An image could not be decoded. Not charged.
- 429: More than 120 calls in a minute for this product.
- 503: The check could not run on our side. Nothing was charged; retry later with the same Idempotency-Key.