Address autocomplete in your web form, validation in your ERP or CRM, geocoding for your route planning. We connect PostcodeAPI.nu, the PostNL Postcode API, Postcode.nl or BAG directly to your application, including caching, fallback flows and an optional offline mode.
Most Dutch postcode APIs deliver perfectly good data. The difference between a pleasant address entry and an irritating form isn't in the provider; it's in how you integrate it. Debouncing, caching, error handling, fallback behaviour when the API is briefly down, and how it feels to the end user who's on a train with a flaky connection. The same provider can feel smooth in one application and frustrating in another, and the difference lies in the implementation choices around it.
We integrate postcode and address APIs into custom software, webshops, B2B portals and mobile apps. For some clients this runs purely in the cloud; for others, such as field service apps or legacy ERPs, we build a hybrid with a local BAG dataset so it also works without an internet connection. Sometimes no external API is the right choice at all, and we connect directly to the Basisregistratie Adressen en Gebouwen (BAG, the Dutch Key Register of Addresses and Buildings). Which approach fits depends on your volume, sensitivity to latency, whether you handle international addresses, and how important the UX at the point of entry is.
For broader integration questions we place the integration within the context of your wider API landscape: how the postcode layer relates to your CRM, order system, carrier integrations and any payment providers. A standalone address component that doesn't move with the rest of your stack only creates maintenance overhead over time.
Which one suits you depends on where address entry takes place, how much volume you handle, and whether it needs to work offline. In the first conversation, we advise which approach fits your situation.
A customer enters a postcode and house number, and the street and town appear automatically. A common approach for webshop checkouts, lead forms and application flows. PostcodeAPI.nu or Postcode.nl as the source, with built-in debouncing and caching, and clear error messages if the API fails to respond. We connect the component to your existing form, whether built in React, Vue, Astro, Livewire or an older framework, without overhauling your front end. Validation runs client-side for quick feedback and server-side for security, and it saves normalised addresses in a consistent format that downstream systems can process.
Clean up existing address data, validate new records at entry, and detect duplicate customers based on normalised addresses. This includes batch validation of your existing database and a scheme for synchronisation whenever address changes occur in BAG. For larger customer databases we first run a data quality report: how many records are incomplete, how many house number additions are missing, which addresses no longer match BAG because a street name has changed. Based on that, we determine which records can be corrected automatically and which need manual attention. The integration works with Exact, AFAS, Twinfield, Microsoft Dynamics, Salesforce, HubSpot and most custom back ends.
For inspectors, engineers and couriers who also work in areas without coverage. We build a local dataset (BAG export or subset) that syncs periodically, plus a fallback to the online API as soon as connectivity returns. On top of that, geocoding for route planning and international coverage via Google or Loqate. The local dataset only contains the regions where your people actually work, which saves considerable storage and sync time. Updates run through FME or an automated feed from PDOK, conflict resolution is predictable (source data wins, with an audit log for manual overrides), and the app itself knows when an area needs to be resynchronised.
A working postcode or address integration in your application, plus everything you need to manage it yourself and keep costs under control.
We don't deliver a black-box component with an API key inside, but code your team can understand and adapt. This includes tests, monitoring hooks and clear documentation of the decisions we made: at what volume a caching upgrade becomes worthwhile, when a second provider makes sense, and how you can expand or reduce the offline dataset yourself.
Four signals that prompt clients to get in touch with us. If you recognise one of them, we'd be glad to continue the conversation.
Customers mistype, forget house number additions, or abandon checkout halfway because the form is fiddly. Autocomplete often halves the number of incorrect deliveries, noticeably shortens checkout and ensures your carrier integration receives correctly formatted addresses. For B2B checkouts, a KvK (Chamber of Commerce) lookup is often combined with address validation, so business customers can be done with a single field.
Your engineers, inspectors or couriers regularly work in places where mobile internet drops out: remote industrial estates, underground car parks, agricultural areas. A hybrid approach, with an offline dataset and a sync mechanism, keeps data entry reliable even without a connection. Once coverage returns, changes sync back to the central database automatically, without the user having to do anything manually.
Your business has grown and the monthly postcode bill is higher than expected. A good caching layer, debouncing and possibly an in-house BAG export can bring costs down without the user noticing anything. For some clients, it also means one shared postcode layer for several applications, instead of a separate bill per app with the same provider.
For property systems, municipalities and housing associations, a direct integration with the Basic Registry of Addresses and Buildings (BAG) is often mandatory or strongly desired. Address data must match the official register exactly, mutations must be traceable and historical address versions must be retrievable. Insurers and mortgage providers face similar data quality pressure: an incorrect house number in an insurance policy is costly to correct afterwards.
We discuss where address entry takes place, what volume you expect, whether international addresses are involved, and whether offline working is a requirement. We also cover which downstream systems need to receive the normalised address, which privacy requirements apply, and how your current checkout or entry flow performs. Based on this, we advise which provider and which architecture fit.
We test one or two providers (PostcodeAPI.nu, PostNL, Postcode.nl or BAG-direct) against your use case. A short proof of concept shows how the UX feels and what the response times are on your real data. For borderline cases, we run the PoC in parallel with two sources so you can experience the difference yourself before committing to a provider and its associated cost structure.
A working build every two weeks. We start with the happy path, then add rate limiting, caching, fallback and, where needed, an offline mode. You test along the way, and we process your feedback in the next sprint. At the end of each sprint you receive a short demo plus an honest status on risks and open points, so there are no surprises at the end.
A phased rollout: first a small share of traffic, then scaling up, with continuous monitoring to confirm the chosen provider keeps delivering. For rate-limit or availability incidents we respond at the agreed service level. After that, you can choose self-management with handover and a runbook, or ongoing management in which we take care of provider upgrades, rate-limit adjustments and new BAG versions.
The questions clients ask before we start, drawn from our conversations and from search results.
A free, no-obligation half-hour introductory call. We listen to your use case, ask about volumes and offline requirements, and advise on which provider and architecture would suit. If it's a good fit, we'll scope a first sprint. If it isn't, we'll tell you honestly. For broader integration questions, we also look at your ERP environment and web applications.
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