Mercury

Mercury’s banking API, for agents that pay vendors, reconcile transactions or watch balances. Mercury’s own sandbox cannot send webhooks, has no way to make a payment fail, return or be blocked, and needs a second person in a dashboard to approve a payment request. This twin settles, fails and returns payments when the environment advances, approves requests by directive, and delivers its event stream to webhook endpoints with Mercury’s own signature. Mercury publishes no client library, so the conformance suite pins the OpenAPI document Mercury’s reference pages carry and validates every response the twin gives against it. Slug: mercury

What it models

Area	Modelled
Starting account	One business organization with its administrator, a checking and a savings account, one ACH recipient and one payment to it still pending
Authentication	A `secret-token:mercury_…_yrucrem` API token as HTTP Basic or `Bearer`; read-only and read-write tokens; Mercury’s three `401`s and its `403` for a write on a read-only token
Organization and accounts	The organization, its users, checking, savings, credit and treasury accounts, with balances projected from their transactions
Transactions	Both transaction lists — one paged by cursor, the older one by offset over the last 30 days — every filter, notes and categories, and settlement, failure, return and blocking on advance
Recipients	Recipients and recipient invites
Send money	ACH, check, wire and real-time payments with the 24-hour duplicate guard and `idempotencyKey`, approval requests a directive approves or rejects, internal transfers
Events and webhooks	The event stream as RFC 7396 merge patches with previous values, webhook endpoints filtered by event type and field, deliveries signed with `Mercury-Signature` and retried
Cards	Virtual cards, frozen, unfrozen and cancelled, in both of Mercury’s card shapes
Categories and merchants	Custom expense categories, and Mercury’s priority merchants
Accounts receivable	Customers and invoices, cancelled, paid and their PDFs
Documents	Monthly statements and their PDFs, treasury statements and transactions, SAFEs, attachments
Errors and paging	Each of Mercury’s error envelopes as production answers them, cursor pagination with `limit` up to 1000, and dollars that keep their cents

Not modelled

OAuth2, custom tokens and their scopes, the IP allowlist a read-write token needs, rate limiting and the MCP server. An endpoint Mercury has and the twin has not built answers an explicit 501 notModeled in Mercury’s envelope; a path Mercury does not have is Mercury’s own 404.

Getting Started

Concepts

Interfaces

Request a twin

What it models

Not modelled

​What it models

​Not modelled

What it models

Not modelled