With growing regulatory demands such as the NIS2 directive, registries across Europe are under pressure to improve the quality of their domain registration data - especially postal address data. However, validating addresses is inherently complex due to global variation in formats, languages, abbreviations, and user behaviour. A rigid comparison with official notations often fails, as people commonly include typos, additional details, or unconventional formatting that still makes sense to a human.
From Isolated Efforts to Joint Innovation
Until recently, each registry was approaching the challenge independently. DENIC, the German registry, had already developed a tool for validating German addresses with high accuracy. Recognising the shared challenge and DENIC’s progress, several registries agreed to join forces through a dedicated task force in CENTR.
Shared Objective, Practical Approach
The goal: adapt and expand DENIC’s tool into a robust, shared tool that can handle real-world address data across multiple countries. The solution needed to reflect how addresses are actually used - accommodating abbreviations, mixed-language inputs, and minor errors. If a human could interpret and deliver to the address, the tool should too.
Collaboration in Action
Seven registries, .de (Germany), .dk (Denmark), .at (Austria), .it (Italy), .nl (The Netherlands), .es (Spain), and .be (Belgium), actively contributed. Each shared knowledge about national address conventions and user behaviour. Participants then tested the tool via a secure, logging-free platform hosted by DENIC, providing feedback based on real address data from their countries. DENIC iteratively improved the tool based on this input.
Results and Open Source Launch
In just six months, DENIC enhanced the tool to support validation for 11 countries. The project, now named OpenPAQ (https://openpaq.de) was released as open source for the broader community. Benchmarking used 90 correct and 40 incorrect addresses per country to assess performance. The tool achieved over 75% accuracy for countries including France, the UK, Poland, Denmark, Italy, and the US. For Germany, the Netherlands, Switzerland, and Austria, it surpassed 90%.
A Shared Standard for the Future
OpenPAQ now offers a foundation for consistent, high-quality address validation across registries. By working collaboratively, registries can deliver standardized results to registrars, while continuing to improve the tool through open contributions.
Article by Robin Gontermann (DENIC, .de)
