This tool allows you to create a barcode in either 39 or 128 format. Format 39 only accepts 0-9, capital A-Z and the following characters: $, %, +, -, . and space. The tool will capitalize your text for Format 39 for you. Format 128 is more robust and accepts a wide variety of ASCII characters including upper and lower case letters, numbers, symbols, etc.
Adapted from CssScript.com