Idempotency - Ledger

How it works

For any POST endpoint, include an Idempotency-Key header to ensure the request is only processed once:

curl -X POST https://api.ledger.so/v1/customers \
  -H "Authorization: Bearer $LEDGER_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: create-customer-abc123" \
  -d '{"email": "dev@example.com", "firstName": "Dev", "lastName": "Example", "type": "individual"}'

If you send the same idempotency key again with the same request, you will receive the original response. Use a fresh key for each logical create operation. If you reuse create-customer-abc123 on POST /v1/customers, Ledger will intentionally return the same customer response again instead of creating a new one.

Rules

Idempotency keys are scoped to the endpoint and HTTP method
Reusing a key for a different route or method returns 409 Conflict
Keys can be any string — UUIDs work well
Keys are only required for POST requests. GET, PATCH, and DELETE are naturally idempotent