Save a bank account as a payment instrument, so you can use it for ACH payments.

Use one of two modes:

• Direct: send the routing and account numbers. They are checked, encrypted and stored in one call.
• Linked: send the bankAccountId of a recipient bank account that already exists.

The response returns an instrument_id, which you then pass as payment_method.instrument_id.

Authenticate with a dashboard session token or a merchant secret key (X-API-Key). A secret key acts only for its own merchant: instruments it creates belong to that merchant, and another merchant's instruments return 404. Publishable, payout_write and agent_onboarding keys are refused. Available to merchant and tenant users.