Barcode Generator

A barcode packs a short string of digits or text into a pattern of black bars and white spaces that a laser or camera scanner can read in a fraction of a second, without anyone needing to type it by hand. Different industries settled on different barcode symbologies (encoding standards) over the decades, and this tool covers the three a small business, hobby project, or student assignment is most likely to need: Code 128, EAN-13, and UPC-A. Code 128 is the most flexible of the three — it can encode any printable ASCII text, not just digits, which makes it the natural choice for shipping labels, internal inventory codes, ticket numbers, or any alphanumeric identifier a point-of-sale scanner needs to read back exactly as typed. This tool implements Code 128 Subset B, the variant built for readable mixed-case text and punctuation, as opposed to Subset C (which packs pairs of digits more densely) or Subset A (aimed at control characters). EAN-13 and UPC-A, by contrast, are strictly numeric retail barcodes — the ones printed on nearly every packaged product sold in a shop. EAN-13 (European Article Number, despite the name now used worldwide) encodes 13 digits; UPC-A (Universal Product Code), the older North American standard, encodes 12. The two are close relatives: a UPC-A code is mathematically identical to an EAN-13 code with an invisible leading zero, which is why an EAN-13 scanner at a checkout can read a UPC-A product without any special handling, and why this tool reuses the exact same encoding tables for both formats. Both EAN-13 and UPC-A end with a check digit — a single digit mathematically derived from every digit before it, using an alternating-weight checksum. Its only job is error detection: if a digit gets mistyped, smudged in print, or misread by a scanner, the check digit almost certainly won't match, so the scanning system can reject the read and ask for another pass rather than silently recording the wrong product. This tool calculates that check digit automatically when you type a 12-digit EAN-13 body (or an 11-digit UPC-A body), and verifies it for you when you type the full code including your own check digit, telling you exactly what value it expected if there's a mismatch. Everything — encoding, checksum calculation, and the canvas drawing itself — runs directly in your browser using plain JavaScript. No text or number you type is ever uploaded anywhere; the finished barcode exists only as pixels on your own screen until you explicitly choose to download it as a PNG.