Produce real, scanner-readable barcodes β Code 128, Code 39, EAN-13, UPC-A and ITF-14 β and download them as vector SVG or a print-resolution PNG. Barcode generator sites charge a subscription for bulk codes, cap how many you may make a day, or quietly put a watermark in the file. The encoding tables here are the published standards, the checksums are calculated for you, and nothing you type is ever sent anywhere.
A scanner reads the ratio of bar to space widths, not the pixel size, so the same SVG prints on a sticky label or a pallet card. Two rules matter more than anything else: leave the quiet zone (the blank margin either side β 10 modules is the usual minimum) and never print a barcode in a single colour on a coloured background. Red, orange and pale yellow bars are invisible to a red laser scanner.
EAN-13 and UPC-A are fixed-length retail codes: 13 and 12 digits. If you type one fewer, the check digit is
calculated and appended; type a full-length code and its check digit is validated, so you will be told if a
supplier's number is wrong. ITF-14 is the carton code used on shipping boxes and wants 14 digits. Code 39 is
the forgiving one β upper-case letters, digits and - . $ / + % and space β while Code 128 packs
the same data into roughly two-thirds of the width by encoding digit pairs together.
The check sums are computed from the published algorithms (mod-103 for Code 128, mod-43 optionally for Code 39, mod-10 for the retail codes). A barcode printed at 4Γ and then shrunk will still scan; one printed at 1 px per module on a cheap inkjet may not.