FreshBooks API vs Merge Accounting API

FreshBooks API

OAuth scopes split read and write per resource, such as user:invoices:read. Rate limits have no numbers, status code or headers.

Merge Accounting API

12 accounting platforms behind one set of common models, with writes. Launch jumps from free to $650 a month at the fourth linked account.

FreshBooks API

1. Call /auth/api/v1/users/me first and keep both ids. Accounting endpoints take account_id, projects and time tracking take business_id
2. Serialise token refreshes. Issuing a new refresh token kills the old one at once
3. Mark an invoice as sent (action_mark_as_sent) or email it. Reports ignore drafts
4. Send x-api-version: 2023-09-25 on journal entry calls
5. Back off on any throttling response yourself. There's no Retry-After to read and no published limit

Merge Accounting API

1. Call GET /invoices/meta/post for the linked account first. Required fields differ by platform
2. Bills and sales invoices are one model. Set type to ACCOUNTS_PAYABLE or ACCOUNTS_RECEIVABLE
3. Append .md to any docs URL for the Markdown twin
4. Check sync_status before reading a freshly linked account. Common models fill in over the first sync
5. Look the record up before retrying a POST that timed out. There's no idempotency key