Barcode Generator

The question I get most from people using this tool isn't how to generate a barcode — it's which format to pick, because there are 10 options and most people just want "a barcode" without knowing the differences matter. They usually do matter, because the scanner or system on the receiving end often expects a specific symbology, not just any barcode that looks right.

How it works

Generation itself is straightforward — JsBarcode takes your input text and the chosen format's encoding rules and draws the corresponding bar pattern, entirely client-side. The part worth understanding is what makes formats different: CODE128 is high-density and handles the full ASCII character set (letters, numbers, symbols), which is why it's the default for general logistics and shipping — it packs the most data into the least space. EAN-13 and UPC-A are fixed-length, numeric-only, retail-specific formats tied to actual product registration through GS1 — you can generate a UPC-A-shaped barcode here for free, but if you want it to scan as a legitimate registered product at a real point-of-sale system, the number itself needs to come from a GS1-issued company prefix, not just any 12 digits. CODE39 is older, lower-density, and letters/digits-only, but it's still what a lot of government, automotive, and healthcare systems specifically require because their scanning hardware was built against that spec decades ago and never changed.

A real example

Say you're labeling internal inventory bins in a small warehouse — not retail products, just "which shelf is this on." CODE128 with a string like "BIN-A14-03" encodes that cleanly, scans fast, and doesn't require registering anything with anyone. Compare that to putting an actual consumer product on a retail shelf: that needs a real EAN-13 or UPC-A with a GS1-registered prefix, or the barcode will scan at checkout as either an error or, worse, as someone else's already-registered product.

Common mistakes

• Using EAN-13/UPC-A for internal or non-retail purposes and assuming it needs to be "correct" like a real product code. For internal use, CODE128 is simpler and doesn't carry the assumption of being a globally unique registered number.
• Printing barcodes too small. Below about 1.5 inches wide, bar widths get thin enough that ordinary retail scanners start missing reads, especially on CODE39 which is already lower density than CODE128. If scans are failing at a register, size is often the actual problem, not the barcode data.
• Low contrast color choices. A barcode in dark blue on a light gray background might look fine to your eye and fail constantly on a scanner. Stick to black bars on white or very light backgrounds unless you've actually tested the specific scanner you'll be using.