Codabar barcode API
Numeric barcode with A to D start and stop letters, used by libraries, blood banks and couriers.

What Codabar is for
Codabar is an older numeric barcode that tolerates low-quality printing, so it has stayed in use in libraries, blood banks, photo labs and on courier airbills. The start and stop letters (A to D) are part of the data and often carry meaning.
Make one from a URL
Send the text and get the image back. Your API key goes in a header.
curl "https://barcode.fmdeploy.com/v2/barcode/codabar?text=A40156B&label=true" \ -H "Authorization: Bearer bc_live_your_key" -o codabar.png
Add &output=svg for a vector image that stays sharp at any print size.
From FileMaker
Insert from URL [ Select ; With dialog: Off ; Target: Items::Barcode ; "https://barcode.fmdeploy.com/v2/barcode/codabar?label=true&text=" & GetAsURLEncoded ( Items::Code ) ; cURL options: "--header \"Authorization: Bearer " & $$BARCODE_KEY & "\"" ]
What it accepts
Digits and the symbols - $ : / . +, wrapped in a start and a stop letter from A to D, for example A40156B. Example: A40156B
If the text can’t be encoded, the API answers with a clear message instead of a broken image.
Options
Set the bar width with scale, the bar height with thickness, and turn the text under the bars on with label. You can also choose the label font and size, rotate the image in quarter turns, set the DPI stored in a PNG, or ask for SVG. The documentation lists every parameter and its default.
Related formats
Try Codabar with a free key
200 barcodes free every month. No card needed.