M
API Matrix

PostcodeData.nl API

Geocoding / No Auth Required Beginner HTTP
Free to Use Varies (check documentation)
80 Score
Grade A
Visit Official Site Compare Alternatives

Overview

PostcodeData.nl provides geolocation and address data for Dutch postal codes. You can look up a postcode with a house number to get the full address, city, province, and GPS coordinates. No API key is required, making it simple to use for Dutch address validation projects.

💡

Beginner Tip

Dutch postcodes follow the format NNNNXX (4 digits + 2 letters, e.g., 1211EP). Always include both the postcode and streetnumber parameters for the most accurate results.

Available Data

IP address details
latitude and longitude
city and country
timezone
ISP information

Example Response

JSON Response 
{
  "ip": "203.0.113.42",
  "city": "San Francisco",
  "region": "California",
  "country_code": "US",
  "latitude": 37.7749,
  "longitude": -122.4194,
  "timezone": "America/Los_Angeles",
  "isp": "Example ISP"
}

Field Reference

postcode The Dutch postcode that was looked up.
street Street name associated with the postcode and house number.
city City or municipality for this address.
province Province within the Netherlands where the address is located.
geo GPS coordinates (lat/lng) of the address location.

Implementation Example 

const url = "http://api.postcodedata.nl/v1/postcode/";
const response = await fetch(url);
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data);

What Can You Build?

Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.

Common Errors & Troubleshooting

Empty or null response for a postcode The postcode and street number combination does not exist in the database.
✓ Verify the postcode is in valid Dutch format (4 digits + 2 uppercase letters) and that the house number is correct.
JSON parse error The type=json parameter may be missing, causing the API to return a different format.
✓ Always include &type=json in your request URL to ensure JSON output.
Server throttle or slow response Too many requests sent in a short period.
✓ Add a delay between requests (at least 1 second) and cache results to avoid repeat lookups.

Matrix Score Breakdown

🌐 Reachability 30/30
⚡ Speed 15/20
🔒 Security 0/15
🛠 Developer XP 20/20
✓ Reliability 15/15
Response Time 287ms

Fully tested on Apr 5, 2026

Technical Specifications

Auth No Auth
HTTPS NO
CORS UNKNOWN
Category Geocoding
Difficulty Beginner
Verified: 2026-04-04

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