IDAutomation offers a few different options for FileMaker barcode integration.
There is a Native generator that generates barcodes without using any external barcode fonts. This is good for when you are distributing files to multiple users.
There is also the option to use an encoder plug-in that will encode your data to be used with the appropriate barcode font, code 128, interleaved 2 of 5, etc.
They also have a universal font, that is one font that allows you to create several different types of barcodes.