PostNL

PostNL's API is reliable and comprehensive for Dutch postal services, supporting both REST and SOAP protocols.

API key authentication is straightforward, with good documentation and Postman collections available. The API covers shipping, tracking, address validation, and pickup point location extensively.

Multiple environments support testing, and the API is being modernized throughout 2025. However, it requires a PostNL account and focuses primarily on Dutch/European shipping. It's excellent for businesses shipping in the Netherlands, offering direct access to the national postal service with reliable tracking and delivery options.