Code 39 Barcode Generator API

Code 39 is one of the earliest alphanumeric linear symbologies, standardized as ISO/IEC 16388. It encodes uppercase letters A-Z, digits 0-9, and seven symbols (space, hyphen, period, dollar sign, slash, plus, percent), with each character represented by nine bars and spaces, three of which are wide. Its self-checking structure and simple decoding logic made it easy for early scanner hardware to implement, and it remains readable by essentially every barcode scanner on the market.

Requesting a Code 39 symbol from BarGen only requires the format parameter set to code39 and an uppercase alphanumeric string; lowercase input is automatically converted since Code 39 has no lowercase letters. Output is available as SVG for label printing workflows or PNG for quick embedding in documents and web pages, with an optional checksum character for higher-assurance applications.

Code 39, also known as Alpha39 or Code 3 of 9, is one of the oldest barcode symbologies still in widespread use. Developed in 1974, it was the first barcode to encode alphabetic characters along with numbers.

The symbology is self-checking, meaning a single printing defect will not cause a wrong character to be read. Each character is represented by 9 elements (5 bars and 4 spaces), where 3 of the 9 elements are wide, giving the code its name.

Code 39 can encode uppercase letters A-Z, digits 0-9, and special characters including space, minus, plus, period, dollar sign, slash, and percent. While it has lower data density than Code 128, its simplicity and reliability make it popular for many applications.

It is the standard barcode used by the United States Department of Defense (LOGMARS) and is widely used in automotive, healthcare, and manufacturing industries.