Code 39

Code 39 is a bar code format which has been standardized as ISO/IEC 16388, ANSI MH 10.8 M-1983, and ANSI/AIM BC1/1995, as well as the obsolete military standard MIL-STD-1189 (superseded by the ANSI/AIM standard). It has a 43-character repertoire including uppercase letters, numbers, and a few punctuation characters.

Among its users is the comic book grader CGC, which includes bar codes of this sort in its encapsulated containers for graded comics. (At least in its original version; the style of the containers has changed since, and it's possible a different bar code type is used.) It is also used on some coupons, and on airline reservation confirmations that are scannable at airport kiosks.

Utilities

 * Bar code generator
 * Another bar code generator

Fonts

 * Free Bar Code 39 font

Developer libraries and modules

 * ZBar bar code reader library: cross-platform
 * zxing (Zebra Crossing) (barcode library for Java, ported to some other systems)
 * MediaWiki extension to generate UPC, EAN, and Code39 codes
 * barcode.php

Other links

 * Wikipedia article
 * Code 39 FAQ and tutorial
 * CGC site (comic grading)