About BarcodesGenerator

BarcodesGenerator makes six kinds of barcodes — Code 128, EAN-13, UPC-A, the ISBN barcode, Code 39, and ITF-14 — entirely in your browser, with SVG and PNG downloads and no account. It is published by Sumvia, the team behind the Sumvia.net utility network. What sets it apart from the hundred other barcode generators is not the bars; it is the arithmetic around them, and the honesty about what a generator cannot do.

The verification layer is the product

Rendering bars is a solved problem — this site uses the pinned, unmodified open-source JsBarcode library for it. What we built on top is an independent verification layer: our own implementations of the GTIN mod-10 check digit, the ISBN-10 mod-11 check and its 978 conversion, the Code 39 character set, and Code 128's code-set rules, each tested against published reference values. Every check digit shown on this site is computed by that layer, and after the renderer encodes a barcode, the check digit is re-derived independently — if the two ever disagreed, you would see an error, not a wrong barcode.

Verify-or-compute, never silently "fix"

Enter 12 EAN digits and the site computes the 13th and says it did. Enter 13 and the site verifies your last digit — and a mismatch is an error naming the expected digit, never a barcode with a quietly substituted check. A wrong check digit usually means a typo somewhere in the data, and "helpfully" correcting it would launder a detectable error into a valid wrong number. The same policy runs through everything: lowercase conversion in Code 39 is disclosed, ISBN conversions show every intermediate number, and characters we cannot encode reliably are refused with the reason.

What a barcode generator cannot give you

Two things, stated on every relevant page. First: numbers. Retail EAN/UPC numbers are licensed from GS1, and ISBNs are issued by national ISBN agencies — no generator can register a number, and an unregistered number will fail retailer validation. Second: optics. We verify mathematics, not your printer's contrast, size, or margins, so every page tells you to test the printed result with a real scanner before production use. Where we cite physical size guidance, the figures come from GS1 sources linked in place.

Browser-native, no accounts

Nothing you type is transmitted, logged, or stored — validation, encoding, and downloads all happen on your device, and the tools keep working on a flaky connection once the page has loaded. There is no registration and no watermark. This is a deliberate design constraint of every Sumvia site.

Tested logic, examples that cannot drift

The verification layer is small, typed, and covered by automated tests whose reference values come from cited published sources — GS1's example GTIN, Wikipedia's check-digit walkthroughs, the canonical ISBN conversion example. The worked examples in page copy are computed at build time by that same code, so documentation and implementation cannot disagree. The full approach, including exactly what the renderer does versus what our layer does, is on the methodology page.

Get in touch

Found a barcode that scans wrong, a check digit you believe is incorrect, or a symbology you need? See the contact page — suspected verification errors are the reports we take most seriously.