Dutch PostNL KIX Barcode API
Netherlands postal service code
Sample Dutch PostNL KIX barcode
Generated live by the BarGen API from 1231FZ13XHS
KIX, short for Klant IndeX, is the four-state postal barcode used by PostNL for domestic mail sorting in the Netherlands. It shares the same visual structure as RM4SCC and IMb, encoding data through ascender, descender, tracker, and full bar heights, but its payload is simply the Dutch postcode and house number with no checksum digit, keeping the symbol short and the encoding straightforward.
Send a Dutch postcode and house number string to the BarGen REST API to generate a KIX symbol, returned as SVG or PNG formatted to PostNL bar height and spacing specifications for envelopes and labels.
KIX (Klant IndeX) is a barcode used by PostNL, the Dutch postal service, for automated mail sorting. It encodes the postcode and house number to enable automated delivery point sorting.
The barcode format is similar to Royal Mail 4-State, using four bar heights to encode data. It can encode uppercase letters and digits, matching the Dutch address format of postcode (4 digits + 2 letters) plus house number.
KIX codes are used for bulk mailings and enable mailers to receive postal discounts. By pre-sorting mail and printing the barcode, mailers reduce PostNL's processing costs and receive reduced postage rates.
The barcode is designed for high-speed automated sorting machines. When printed according to PostNL specifications, mail pieces can be sorted to the individual delivery point without manual intervention.
Common use cases
Dutch domestic mail sorting
PostNL sorting centers scan KIX codes to route letters directly by postcode and house number without OCR of the address block.
Direct mail and invoicing
Dutch billing and direct mail printers include KIX codes on window envelopes to speed up PostNL processing.
Return mail handling
Business reply envelopes in the Netherlands use KIX to let automated equipment identify the sender's return address quickly.
Generate Dutch PostNL KIX via the REST API
curl "https://api.bargen.pro/v1/barcode/kix?data=1231FZ13XHS&format=svg" \
-H "X-API-Key: YOUR_API_KEY"Returns the barcode as SVG; PNG, PDF and EPS are available on higher plans. See the API documentation for all options.
Frequently asked questions
Does the KIX code include a check digit?
No, unlike RM4SCC and IMb, KIX has no checksum character, which keeps the symbol shorter but means printing accuracy matters more for reliable decoding.
What data goes into a KIX barcode?
A KIX code typically encodes the Dutch postcode, house number, and any house number addition, letting PostNL sorting machines resolve the exact delivery address.
Can KIX be printed on standard office printers?
Yes, KIX only requires a font or barcode renderer capable of producing the four-state bar heights, so it can be added to invoices and letters via standard document generation tools.
Specifications
- Character Set
- A-Z, 0-9
- Structure
- Postcode (4 digits + 2 letters) + House number
- Bar States
- 4 (full, ascender, descender, tracker)
Related formats
Start generating Dutch PostNL KIX barcodes
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