Sinbad Partner API

curl -X POST https://us-central1-sinbad-staging-env.cloudfunctions.net/b2b-v1/v1/trades/trade_demo/proof \
     -H "Authorization: Bearer <token>" \
     -H "Content-Type: application/json" \
     -d '{
  "contentType": "image/png",
  "dataBase64": "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP8/x8AAwMCAO+/lS8AAAAASUVORK5CYII="
}'

{
  "proofId": "proof_demo",
  "contentType": "image/png",
  "size": 68,
  "uploadedByRole": "customer",
  "uploadedAt": "2026-10-23T10:00:00.000Z",
  "base64": "/9j/2wBDABQODxIPDRQSEBIXFRQYHjIhHhwcHj0sLiQySUBMS0dARkVQWnNiUFVtVkVGZIhlbXd7gYKBTmCNl4x9lnN+gXz/2wBDARUXFx4aHjshITt8U0ZTfHx8fHx8fHx8fHx8fHx8fHx8fHx8fHx8fHx8fHx8fHx8fHx8fHx8fHx8fHx8fHx8fHz/wAARCABAAEADASIAAhEBAxEB/8QAFQABAQAAAAAAAAAAAAAAAAAAAAb/xAAUEAEAAAAAAAAAAAAAAAAAAAAA/8QAFAEBAAAAAAAAAAAAAAAAAAAAAP/EABQRAQAAAAAAAAAAAAAAAAAAAAD/2gAMAwEAAhEDEQA/ALMAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH/2Q==",
  "width": 1,
  "height": 1
}

Upload payment proof.

Credential: Customer session

Before you call

A customer session for the same partner, integration, customer, wallet and chain.
To change proof, the customer must be the fiat payer on a BUY, and the trade must be CREATED, PAID or DISPUTED.
Uploads accept PNG or JPEG files up to 3 MiB decoded. Authenticated reads return merchant originals unchanged.

Customer BUY fiat payer only in CREATED, PAID or DISPUTED. One PNG or JPEG image up to 3 MiB. PDFs are rejected for new uploads. Identical POST retry is idempotent; use PATCH for replacement. Stored privately with a small blurred preview; a linked proof message is committed atomically. Does not mark paid.

Storage unavailability can return 502 or 503 UPSTREAM_ERROR. Retry with backoff; contact Sinbad with requestId if it persists.

Confirm with Sinbad that this endpoint is enabled in your environment.

Errors

Status	Code	What to do
400	`VALIDATION_ERROR`	Correct the fields reported in details before retrying.
401	`UNAUTHENTICATED`	Create a new customer session or use a valid server credential.
403	`FORBIDDEN`	Check credential ownership, integration and the supplied Origin.
404	`NOT_FOUND`	Check the resource ID. A resource that belongs to someone else also returns 404.
409	`CONFLICT`	Read the current state again before you prepare or retry.
502	`UPSTREAM_ERROR`	Retry with backoff and quote requestId if it persists. For transaction reports, retry the same hash without sending another transaction.
503	`UPSTREAM_ERROR`	Retry with backoff; preserve the same idempotency key for a repeated mutation.

Authentication

AuthorizationBearer

Bearer authentication of the form Bearer <token>, where token is your auth token.

Path parameters

tradeIdstringRequired

Request

This endpoint expects an object.

contentTypeenumRequired

Allowed values:

dataBase64stringRequired

Base64 encoded file bytes without a data URL prefix.

Response

Saved proof metadata, including identical retries.

proofIdstring

contentTypestring

Original content type; merchant files can use native image formats.

sizeinteger>=1

uploadedByRoleenum

Allowed values:

uploadedAtdatetime or null

base64string

Blurred preview, not original file bytes.

widthdouble>=0

heightdouble>=0

Errors

400

Bad Request Error

401

Unauthorized Error

403

Forbidden Error

404

Not Found Error

409

Conflict Error

502

Bad Gateway Error

503

Service Unavailable Error