Twinfield API: connect Twinfield to your webshop, CRM and payments

What you can do with the Twinfield API

• Sales invoices from your webshop or CRM as entries in Twinfield
• Keep contacts (debtors and creditors) in sync with your CRM
• Prepare payments from Mollie or the bank for reconciliation
• Fetch outstanding items for reminders and dashboards
• Prepare purchase invoices from your email for processing

How the integration works

The integration signs in through OpenID Connect with a client registered in the Twinfield developer portal. Every call goes to the web service of your cluster, with the company code in the call. Twinfield counts credits per minute; the integration therefore works in batches and respects the wait time Twinfield returns. Every entry gets a fixed reference, so retries are safe.

Facts about the Twinfield API

Checked on 2 November 2026 against the official documentation. Limits, prices and versions change; the source is listed per row.

Fact	What the documentation says	Source
Authentication	OpenID Connect (OAuth 2.0) with the authorization code flow; you register a client in the developer portal. The access token travels with the company code in the SOAP call.	Twinfield: OpenID Connect
Token lifetime	Access token 1 hour in the code flow. Refresh token 25 years, with the offline_access scope.	Twinfield: OpenID Connect
Rate limits	Credits per minute since 1 December 2024: 500 per client and organisation combined, 1,000 per client and 1,000 per organisation. Reads cost 1 credit, writes 3. When exceeded, 429 with Retry-After; at most 10 concurrent calls per client and organisation.	Twinfield: Fair use policy
Webhooks	Not in the official documentation.	Twinfield: Web services
Test environment	A test account goes through the Wolters Kluwer partner programme; conditions not publicly documented.	Twinfield: Documentation
Version and deprecations	SOAP web services (ProcessXML, Finder, bank book, budget, documents and more). Breaking changes with end dates: among others more than 1,000 lines per transaction returns 400 (since October 2024) and ProcessXmlCompressed has ended (July 2025).	Twinfield: Breaking changes
API cost	Not in the official documentation; with structurally high use Twinfield may ask you to reduce it or raise the fee.	Twinfield: Fair use policy
n8n	No built-in node and no community node found; the integration runs through an HTTP step in n8n.	n8n documentation

What you need on your side

• A client in Twinfield's developer portal, or access through your accountant who already has one
• The company code and a user with permissions on that administration
• The VAT codes and ledger accounts per item or service, aligned with your accountant
• A fixed reference per invoice or entry, so nothing is booked twice

Where it often goes wrong, and how I prevent it

• Credits per minute: Twinfield limits the number of calls per minute and per client. An integration that does everything at once runs into a 429. The integration spreads the work.
• Wrong cluster: every organisation runs on its own cluster. The integration asks Twinfield for the right address first instead of hard-coding it.
• Large entries: Twinfield refuses a transaction with more than a thousand lines. The integration splits where needed.
• VAT and ledger: I agree the mapping of VAT codes and ledger accounts with you or your accountant before anything is booked.

In practice

A Twinfield integration is not yet listed as In production with me. The approach is the same as for Exact Online: first against a test environment, a fixed reference per entry, respect for the provider's limits, and a plain-language notification when something fails.

What it costs

I build a Twinfield integration as one scoped process for a fixed price, from €750. Maintenance and monitoring are a monthly fee: n8n management from €250 per month, server management €145 per server. In the free assessment we work out your process. All prices and what is included →

What I do not do

• I do not do your bookkeeping; the VAT and ledger mapping comes from you or your accountant.
• I do not knowingly exceed Twinfield's credits; the integration waits when Twinfield asks.
• I do not build on web services Twinfield has retired.

Frequently asked questions about the Twinfield API

Does n8n have a Twinfield node?

No, and no community node was found either. I connect Twinfield through the web services with an HTTP step in n8n. That is custom work, but readable and yours.

How do I get access to the Twinfield API?

Through a client in Twinfield's developer portal. The link to a test account goes through the Wolters Kluwer partner programme. The conditions attached are not in the public documentation; we check them together.

How many calls per minute does Twinfield allow?

Twinfield works with credits per minute: 500 per combination of client and organisation, and 1,000 per client or per organisation. A read call costs one credit, a write call three. Above that Twinfield returns a 429 with a wait time.

Does Twinfield have webhooks?

Not according to the official documentation. The integration therefore checks at fixed intervals for new or changed data and keeps track of what has already been processed.

What happens when an entry fails?

The entry goes to a queue and you get an error email with what went wrong and what you can do. Temporary errors, such as a limit, are retried automatically later.