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--- title: "How to Integrate With the SnelStart API" description: "A technical guide to integrating with the SnelStart B2B API. Covers authentication, key endpoints, the certification process, and common challenges developers face when building accounting integrations for the Dutch market." author: "GJ" published: "2026-03-18" updated: "2026-03-18T20:48:43.018Z" url: "https://www.apideck.com/blog/how-to-integrate-with-the-snelstart-api" category: "Accounting" tags: ["Accounting", "Guides & Tutorials"] --- # How to Integrate With the SnelStart API SnelStart is one of the most widely used accounting platforms in the Netherlands. It serves freelancers, small and medium-sized businesses, and accounting firms with bookkeeping, invoicing, VAT filing, and bank reconciliation. If you are building software that touches financial data for the Dutch market, SnelStart integration is likely on your roadmap. This guide covers what you need to know to integrate with the SnelStart B2B API, from authentication and available endpoints to the certification process and the common pitfalls that make this integration more complex than it first appears. ## What SnelStart covers SnelStart has been around for over 40 years. It started as a desktop bookkeeping program on Texel and has since grown into a full platform available in both desktop (SnelStart 12) and cloud (SnelStart Web) versions. The product handles core accounting workflows including general ledger management, accounts payable and receivable, invoicing, VAT and ICP declarations, bank statement imports, and inventory management through their InHandel add-on. For accountants and bookkeepers, SnelStart offers a dedicated Accountant package with multi-client management, an integrated tax filing module, and a centralized dashboard. It connects to major Dutch banks including Rabobank, ABN AMRO, ING, Knab, Triodos, and RegioBank. In mid-2025, SnelStart acquired embedded finance company [Flow](https://www.withflow.com/) and launched SnelStart Bankieren, a fully integrated banking product with Adyen providing the underlying banking infrastructure. This puts bank accounts directly inside the accounting interface, eliminating the need to switch between banking and bookkeeping tools. ## API overview The SnelStart B2B API is a REST API hosted on Microsoft Azure API Management. The current version is v2, and the base URL is `https://b2bapi.snelstart.nl/v2`. The API documentation is auto-generated and available through the [SnelStart Developer Portal](https://b2bapi-developer.snelstart.nl/), but only after you register for an account. The documentation is exclusively in Dutch, which creates an extra barrier for international development teams. The API covers a broad set of accounting resources. Key endpoints include: - Artikelen (articles/products) - Relaties (contacts/relations) - Verkoopboekingen (sales bookings) - Inkoopboekingen (purchase bookings) - Memoriaalboekingen (journal entries) - Grootboekrekeningen (general ledger accounts) - BTW-tarieven (VAT rates) - Bankafschriftbestanden (bank statement files) - Documenten (documents) - Facturen (invoices) - Landen (countries) The API supports standard CRUD operations on most resources. You can also import bank statements in MT940, CAMT.053, and CSV formats, as well as UBL invoices. OCR processing is available for scanned documents. ## Authentication This is where SnelStart diverges significantly from other [accounting APIs](https://www.apideck.com/accounting-api). There is no standard OAuth 2.0 flow. Instead, SnelStart uses a multi-layered authentication setup that requires careful credential management. You need three things to make API calls: 1. A subscription key from the SnelStart Developer Portal. You get this by subscribing to a product plan (start with the Ontwikkeling & Test plan for development). 2. A connection key (maatwerksleutel) generated from within the SnelStart web application under Koppelingen > Maatwerk. 3. An access token obtained by exchanging the connection key at the token endpoint (`https://auth.snelstart.nl/b2b/token`). The access token expires every hour. Every API request must include both the subscription key (as a header) and the current access token. This means you need to build automated token refresh logic, handle expiration errors gracefully, and store credentials securely. In a multi-tenant SaaS architecture where you are managing connections for multiple end users, this adds real operational complexity. Each customer's connection key needs to be stored separately, and you need to manage token lifecycle per connection. Here is a simplified authentication flow in pseudocode: ``` // Step 1: Exchange connection key for access token POST https://auth.snelstart.nl/b2b/token Body: { "clientKey": "

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