Introduction - Blackswan

The Blackswan partner-facing HTTP API for customers, loans, repayments, and credit decisions.

What this API gives you

Create and manage customer (borrower) records, including activation and closure.

Origination in a single call — POST /v1/loans submits, approves, and disburses. Reversals available for operational rollbacks.

Record repayments, waivers, refunds, and adjustments against active loans.

Look up a customer’s credit grade and limit, or boost their limit with a financial statement PDF.

String IDs

Every resource ID is exposed as a string. Pass them back exactly as you received them — never reformat or parse.

ISO-8601 dates

All dates on the wire are YYYY-MM-DD.

Bearer-token auth

Every endpoint requires a JWT in the Authorization header. See Authentication.

Errors as structured codes

Failures return a stable error code (not_found, invalid_argument, unauthenticated, …) plus a message. See Errors.

Address resources by partner externalId

Customers, loans, and credit-scoring lookups all accept a partner-supplied externalId alongside the LMS numeric id. You can:

Look up customers by externalId: GET /v1/customers?externalId=X or GET /v1/customers/external/{externalId}
Filter a customer’s loans: GET /v1/loans?customerExternalId=X
Post repayments by the loan’s externalId: POST /v1/loans/external/{loan_external_id}/repayments
Score a customer by externalId: GET /v1/credit-scorecard/{externalId}

Use whichever id you already hold — the wrapper does the lookup. See IDs, dates, and money for the full addressing convention.

Ready to start? Head to the Quickstart.

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