The OpenSettle API is organized around REST. It uses resource-oriented URLs, accepts form-encoded and JSON request bodies, and returns JSON. Versioned by date; current version is 2026-04-01.
https://api.opensettle.comAuthenticate by including your secret API key as HTTP Basic auth username. You don't need to include a password — leave it blank.
curl https://api.opensettle.com/v1/payments \
-u sk_live_xxxxxxxxxxxxxxxxxxxxxxxxa2E1:Errors use standard HTTP status codes. Our body is a typed shape with a machine-readable code, a human-readable message, and — when applicable — a request ID for support.
{
"error": {
"type": "invalid_request",
"code": "settlement_wallet_unverified",
"message": "The settlement wallet has not completed verification.",
"request_id": "req_01HGKM4Z7WQ4X"
}
}