USPS POSTNET Barcode Generator API

POSTNET, short for Postal Numeric Encoding Technique, was the USPS barcode standard for automated mail sorting from the 1980s until it was officially retired for postal discounts in January 2013, when the Intelligent Mail Barcode took over. It encodes a 5-digit ZIP, 9-digit ZIP+4, or 11-digit delivery point code as a series of tall and short bars, with a checksum digit ensuring the ZIP code was read correctly.

BarGen generates a POSTNET symbol from a 5, 9, or 11 digit numeric string via the REST API, returning SVG or PNG output useful for reproducing legacy mail pieces, historical document systems, or reference materials.

POSTNET (Postal Numeric Encoding Technique) was the barcode used by the United States Postal Service from 1983 to 2013 for encoding ZIP codes on mail. It has been replaced by the Intelligent Mail Barcode but is still recognized by USPS equipment.

The barcode uses two bar heights (full and half) to encode numeric data. Each digit is represented by a pattern of five bars, with exactly two tall bars per digit. Frame bars at the start and end ensure proper scanning.

POSTNET can encode 5-digit ZIP codes, 9-digit ZIP+4 codes, or 11-digit Delivery Point Barcodes (DPBC). The 11-digit version includes the ZIP+4 plus a 2-digit delivery point code for the specific address.

While no longer required for postal discounts (IMB is now used), POSTNET remains widely supported for legacy systems. Some mailers continue to use it for internal tracking or when interfacing with older sorting equipment.