Code 39 Barcode Generator

Code 128 unless something specifically demands Code 39. Code 128 handles lowercase, is roughly half the width for the same data, and is read by everything modern. Code 39 survives because of legacy specs - defence logistics, some automotive and healthcare systems - not because it is better.

Standard Code 39 has no lowercase. There is an extension, Full ASCII Code 39, that encodes lowercase as two-character escape sequences, but scanners must be configured for it and many are not. Uppercase your value, or switch to Code 128.

They are the start and stop characters and are added for you. If you type them into the value you will produce a barcode with doubled delimiters that most scanners refuse.

Optionally - a modulo-43 check character. It is not part of the base spec and most implementations omit it, so only add one if the receiving system explicitly asks for it.

Every character is a fixed nine elements, three of them wide, with no compression for digits. A 10-character value produces a noticeably longer symbol than the same value in Code 128 subset C.

Between 2:1 and 3:1, with 3:1 scanning most reliably. Below 2:1 scanners cannot tell wide bars from narrow ones and read rates fall away.

Yes, space is a valid character in the set. It is one of the few symbologies where a space inside the value is entirely legitimate.

Yes - two names for the same symbology. The name comes from the encoding: nine elements per character, three of them wide.