Free barcode generator

Nearly every barcode question comes down to one decision: is this symbol going to be scanned at a retail till, or somewhere you control? If it is retail, you need an EAN or UPC number allocated to you by GS1; a generator cannot give you one, and a made-up number will be rejected or will collide with someone else's product.

For everything else — warehouse shelves, asset tags, event tickets, library stock, a label on a box you are posting — pick Code 128. It takes any ASCII text, packs digits efficiently, and needs no registration. Reach for a 2D format instead when you have more data than a line of bars can carry: Data Matrix when the label is tiny, PDF417 when you need a paragraph of text, and Aztec when the code has to work with no margin around it, such as on a phone screen at a ticket barrier.

To encode a web address, use a QR code rather than a linear barcode. Linear symbologies were designed for short identifiers, and a full URL in Code 128 produces a symbol so wide that most scanners struggle.

Unlike a QR code, a linear barcode cannot encode arbitrary data in an arbitrary format. Each symbology enforces a length and a character set, and bwip-js refuses to render something invalid rather than producing a symbol that will not scan. Almost every error message comes from one of these:

• A retail format given the wrong number of digits. EAN-13 wants 12 or 13, UPC-A 11 or 12, EAN-8 7 or 8.
• Letters in a numeric-only format. EAN, UPC, ITF-14 and Interleaved 2 of 5 accept digits only.
• An odd number of digits in Interleaved 2 of 5, which encodes digits in pairs.
• Lowercase letters in Code 39, which only knows uppercase.
• A check digit you typed yourself that does not match the one the standard computes. Leave it off and let the generator calculate it.

Export SVG whenever the barcode will be printed. A vector file keeps the bar edges crisp at any size, while a PNG scaled up in a layout program produces soft edges that cheap laser scanners misread. Keep the code black on white: scanners threshold the image, and coloured or reversed bars are a common cause of failure.

Leave the quiet zone alone — the blank margin on each side of the symbol is part of the symbology, not decoration, and cropping it is the single most frequent reason a correctly generated barcode will not scan. Do not stretch the symbol horizontally either; narrowing the bars below the printer's resolution destroys it.

Finally, the SVG shape mask option is artwork only. Clipping the bars into a silhouette removes part of the encoded data, so a masked barcode is not readable by design. It looks excellent on a poster and it will never work at a till.