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API versioning overview

Marmin uses a request header to control which API contract applies to each call.

Send `X-MARMIN-VERSION` on every request. Use the same value for all calls in a single workflow (for example, create an invoice, then check its status).

Available versions
VersionDescription
20260101Baseline contract. Use this for existing integrations unless you have tested a newer version.
20260507Latest contract. Includes recent payload changes — see the API change log and Integrator migration guide.
Choosing a version

We recommend always sending the header. This way you control which contract applies, regardless of your account default.

  • Current / stable contract: X-MARMIN-VERSION: 20260101

  • Latest contract: X-MARMIN-VERSION: 20260507 — test in sandbox before using in production.

If you omit the header, Marmin uses your organization's default version. Most accounts default to 20260101. If you are unsure, set the header explicitly or contact support@marmin.ai.

Examples

Baseline contract:

POST /api/sales-invoices/{business_profile_id}
Authorization: Bearer <access_token>
Content-Type: application/json
X-MARMIN-VERSION: 20260101

Latest contract:

POST /api/sales-invoices/{business_profile_id}
Authorization: Bearer <access_token>
Content-Type: application/json
X-MARMIN-VERSION: 20260507
Invalid values

The version must be a date in YYYYMMDD format (for example, 20260101). An invalid value returns 400 Bad Request.

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