Response shape

Every response is enveloped:

{ "success": true, "data": { }, "meta": { "timestamp": "…", "requestId": "…" } }

Failures keep the envelope and replace data with error:

{ "success": false, "error": { "code": "VALIDATION_ERROR", "message": "Validation failed", "details": [] }, "meta": { } }

Branch on error.code, never on message — codes are stable, prose is not. Quote meta.requestId in any support request; it is also returned as the X-Request-Id header.

Rates are strings, not JSON numbers. "155.234000" survives a round trip exactly; 155.234 as an IEEE-754 double does not. Parse them with a decimal type, not parseFloat, if you intend to do arithmetic on them.