> ## Documentation Index > Fetch the complete documentation index at: https://docs.samsa.ai/llms.txt > Use this file to discover all available pages before exploring further. # Check an image or video > Upload one asset and get a per-technique detection result, with the C2PA verdict as the authoritative answer. ``` POST https://detect.samsa.ai/v1/public/detect ``` Upload a single image or video as `multipart/form-data`. The response carries one top-level `detected` verdict plus a per-technique breakdown. No authentication, no credits. The upload is processed **in memory and never retained**. ## Request Send exactly **one** file part named `file`. The part must carry a `filename` in its `Content-Disposition` header — a plain form field without one is not a file part. | | | | ----------------- | ------------------------------------ | | **Content-Type** | `multipart/form-data` | | **Field** | `file` — the image or video to check | | **Max size** | 50 MB | | **Image formats** | JPEG, PNG, WebP, GIF | | **Video formats** | MP4, QuickTime, WebM | JPEG/PNG/WebP/GIF and MP4/QuickTime are recognised by magic bytes, so a wrong or generic part `Content-Type` (for example `application/octet-stream`) does not break detection for those formats. **WebM has no magic-byte branch** and is accepted only when the part declares `Content-Type: video/webm`. ```bash curl theme={null} curl -X POST https://detect.samsa.ai/v1/public/detect \ -F "file=@photo.jpg" ``` ```python Python theme={null} import requests with open("photo.jpg", "rb") as fh: response = requests.post( "https://detect.samsa.ai/v1/public/detect", files={"file": ("photo.jpg", fh, "image/jpeg")}, timeout=120, ) response.raise_for_status() result = response.json() print(result["detected"]) ``` ```typescript TypeScript theme={null} import { readFile } from "node:fs/promises"; const form = new FormData(); // The third argument sets the part filename — required for it to count as a file part. form.append("file", new Blob([await readFile("photo.jpg")]), "photo.jpg"); const response = await fetch("https://detect.samsa.ai/v1/public/detect", { method: "POST", body: form, }); if (!response.ok) { const { detail } = await response.json(); throw new Error(`Detection failed (${response.status}): ${detail}`); } const result = await response.json(); console.log(result.detected); ``` ## Response `200 OK`. An image or video that carries a valid, trusted Samsa C2PA manifest: ```json Response theme={null} { "request_id": "c1a2b3d4-e5f6-4a7b-8c9d-0e1f2a3b4c5d", "detected": "samsa", "techniques": [ { "type": "metadata", "result": "samsa", "confidence": "high", "manifest": { "claim_generator": "Samsa/1.0", "digital_source_type": "http://cv.iptc.org/newscodes/digitalsourcetype/trainedAlgorithmicMedia", "upstream_provider": "fal", "upstream_model": "flux-pro", "timestamp": "2026-07-02T14:21:07+00:00", "assertions": ["c2pa.actions", "c2pa.hash.data"] } }, { "type": "watermark", "result": "not_checked", "confidence": null, "vendor_id": null }, { "type": "watermark", "result": "not_checked", "confidence": null, "vendor_id": null } ], "external_verification": { "c2pa": "https://verify.contentauthenticity.org" }, "result_pdf_url": "https://detect.samsa.ai/v1/public/detect/result/c1a2b3d4-e5f6-4a7b-8c9d-0e1f2a3b4c5d/pdf", "responded_at": "2026-07-02T14:21:09.412093Z" } ``` | Field | Type | Description | | ----------------------- | ----------------- | ----------------------------------------------------------------------------------------------------------- | | `request_id` | string (UUID) | Server-generated id for this check. Use it to fetch the [signed result PDF](/content-verification/results). | | `detected` | enum | The top-level verdict: `samsa`, `non_samsa`, or `unknown`. | | `techniques[]` | array | One entry per technique that was applied — see [below](#reading-the-techniques-breakdown). | | `external_verification` | object | Links for verifying the result independently of Samsa. Currently `c2pa`. | | `result_pdf_url` | string \| null | Link to the signed PDF of this result, or `null` when result persistence is unavailable. | | `responded_at` | string (ISO 8601) | When the check completed, in UTC. | `result_pdf_url` may be `null`. When it is present, follow it exactly as returned rather than assembling the URL yourself — the returned URL and the [documented result endpoint](/content-verification/results) serve the identical signed PDF. ### The `detected` verdict The verdict comes from C2PA manifest verification, which is authoritative. Watermark techniques are corroboration: they can supply attribution when no manifest is present, but they never override a manifest verdict. | `detected` | Reached when | | ----------- | ---------------------------------------------------------------------------------------------------------------------------------- | | `samsa` | A valid, trusted, allowlisted Samsa manifest was verified — or, with no manifest present, a watermark decode returned a Samsa hit. | | `non_samsa` | A manifest is present but is not attributable to Samsa (another issuer, untrusted, or tampered). | | `unknown` | No manifest is present and no watermark hit was returned. | `unknown` means **this check found no evidence**, not that the asset is authentic or human-made. Provenance metadata is easily stripped, and hosted watermark decode is [not yet available](#reading-the-techniques-breakdown). ## Reading the techniques breakdown `techniques[]` always starts with the single `metadata` entry (the authoritative C2PA layer), followed by the watermark techniques applicable to the asset's modality. ### The `metadata` technique ```json theme={null} { "type": "metadata", "result": "absent", "confidence": "low", "manifest": null } ``` | Field | Description | | ------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `result` | `samsa` (valid, trusted, allowlisted Samsa manifest), `non_samsa` (a manifest from another issuer, or one that is valid but untrusted), `tampered` (a manifest that fails validation), or `absent` (no manifest — commonly because it was stripped). | | `confidence` | `high`, `medium`, or `low`. Always present for this technique. | | `manifest` | A layperson-readable summary of the verified manifest (`claim_generator`, `digital_source_type`, `upstream_provider`, `upstream_model`, `timestamp`, `assertions`), or `null` when there is nothing to summarize. | C2PA manifest verification is **live**: it is served by the Samsa public API and by any independent C2PA validator. Attribution of a manifest to Samsa becomes available once production signing is enabled. ### Watermark techniques ```json theme={null} { "type": "watermark", "result": "not_checked", "confidence": null, "vendor_id": null } ``` | Field | Description | | ------------ | --------------------------------------------------------------------------------------------------------------- | | `result` | `samsa`, `absent`, `low_confidence`, or `not_checked` — see the table below. | | `confidence` | `high`, `medium`, or `low`, and `null` **if and only if** `result` is `not_checked`. The key is always present. | | `vendor_id` | Identifies the decoder that produced a hit; `null` unless `result` is `samsa`. | | `result` | Meaning | | ---------------- | --------------------------------------------------------------------------------- | | `samsa` | A decoder ran and found a Samsa watermark. | | `absent` | A decoder ran and found no Samsa watermark. | | `low_confidence` | A decoder ran and returned a weak hit. | | `not_checked` | The decoder backend is not provisioned, so **the technique was never evaluated**. | `not_checked` is **not** a statement that no watermark is present — that is what `absent` means. Hosted watermark decode is not yet available; it is scheduled before 2 February 2027. Until then the API reports these techniques as `not_checked`, never as a false “no watermark”. Never render a `not_checked` technique as an absent watermark. Because hosted watermark decode is not yet live, every watermark entry currently comes back as `not_checked` with `confidence: null`. Watermark entries carry no technique name of their own — for the algorithm IDs, pinned model artifact hashes, per-lane soft-binding labels, and open-source decoders behind each technique, read [How detection works](https://detect.samsa.ai/how-detection-works) or [`GET /v1/public/detect/info`](/content-verification/info). ## Errors Errors return `{"detail": "…"}` — not the Samsa REST API [error envelope](/guides/errors). | Status | When | | ------ | ---------------------------------------------------------------------------------------------------------------- | | `400` | Malformed multipart body, a missing boundary, an empty upload, or a file-part count other than exactly one. | | `413` | The upload exceeds the 50 MB limit. | | `415` | The request is not `multipart/form-data`, or the uploaded bytes are not a supported image or video. | | `503` | An available decoder or the C2PA verifier failed at inference time. The response carries a `Retry-After` header. | Treat `503` as transient and retry after the `Retry-After` interval. A decoder that is simply not provisioned never produces a `503` — it degrades to `not_checked` in a normal `200` response.