KVK API vs Government API: Which Should You Choose?

There are several ways to programmatically access Dutch company data. The right API depends on your use case, budget, and technical requirements. In this article we compare the four most commonly used options: the official KVK API, OpenKVK, Overheid.io, and KVKBase.

The options at a glance

1. Official KVK API (KVK Trade Register API)

The Chamber of Commerce itself offers an API. This is the primary source of all trade register data. The API is available through the KVK Developer Portal and requires a separate contract.

Strengths:

• Most complete and up-to-date data
• Official source
• Search, lookup, and basic profiles available

Drawbacks:

• Complex sign-up process
• Cost per request
• Documentation can be technical and verbose
• No VAT information included

2. OpenKVK

OpenKVK was a popular open-source initiative that made KVK data available through a free API. The project played an important role in making business data accessible to developers.

Strengths:

• Free
• Simple API

Drawbacks:

• Data can be outdated
• Limited availability and maintenance
• No uptime guarantee
• Limited fields available

3. Overheid.io

Overheid.io provides access to various government registers, including the trade register. It focuses on making open government data available.

Strengths:

• Broad dataset (not just KVK)
• Dutch provider
• Reasonable documentation

Drawbacks:

• Rate limits on the free plan
• Data is not always real-time
• API design follows its own conventions

4. KVKBase

KVKBase is built specifically for developers who want fast and reliable access to Dutch company data. The focus is on simplicity, speed, and developer experience.

Strengths:

• Fast JSON REST API
• Includes VAT/VIES validation
• Embeddable widget for frontends
• Modern documentation
• Predictable pricing

Drawbacks:

• Paid product (free tier available)
• Newer in the market

Comparison table

Feature	KVK API	OpenKVK	Overheid.io	KVKBase
Data freshness	Real-time	Delayed	Periodic	Daily
Price	Per request	Free	Freemium	Freemium
VAT data	No	No	Limited	Yes
VIES validation	No	No	No	Yes
Response format	JSON/XML	JSON	JSON	JSON
Rate limits	Contract	Unknown	Yes	Yes (generous)
Embeddable widget	No	No	No	Yes
Search by name	Yes	Yes	Yes	Yes
Search by KVK number	Yes	Yes	Yes	Yes
SBI codes	Yes	Limited	Yes	Yes
Branch data	Yes	Limited	Limited	Yes
Documentation	Fair	Limited	Reasonable	Good
Sign-up process	Complex	None	Simple	Simple

Which should you choose?

Choose the official KVK API if…

…you work for a large organization with legal requirements for direct data access from the source. The official API is the only option if you are contractually required to obtain data directly from the KVK, or if you need the most complete dataset including historical data.

Keep in mind that the sign-up process can take weeks and that per-request costs can add up.

Choose OpenKVK if…

…you are building a hobby project or want to quickly prototype something without costs. The limited reliability and data freshness make it less suitable for production environments.

Choose Overheid.io if…

…you need access to other government registers in addition to KVK data. The platform offers a broad dataset that goes beyond just the trade register.

Choose KVKBase if…

…you are a developer who wants to quickly build a reliable integration. KVKBase is specifically designed for the most common use cases: looking up a company, validating data, and auto-filling forms. The combination of KVK data and VAT/VIES validation in a single API saves you from integrating multiple services.

Technical comparison: a lookup in practice

Here is what a simple lookup looks like with each API:

KVKBase:

curl -H "Authorization: Bearer $API_KEY" \
  "https://api.kvkbase.nl/api/v1/lookup/12345678"

Official KVK API:

curl -H "apikey: $KVK_API_KEY" \
  "https://api.kvk.nl/api/v1/basisprofielen/12345678"

The difference is not so much in the call itself, but in what you get back, how fast it is, and how much work you need to do to process the response.

Combining sources

In practice, you can also combine sources. For example, use KVKBase for daily lookups in your application and the official KVK API for specific legal verifications where you need the primary source.

Conclusion

There is no one-size-fits-all solution. The right choice depends on your specific requirements:

• Completeness and official source: KVK API
• Free prototyping: OpenKVK
• Broad government data: Overheid.io
• Developer experience and speed: KVKBase

For most SaaS applications and B2B platforms, KVKBase offers the best balance of functionality, reliability, and ease of use. But always evaluate based on your own situation.