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. Barcode or QR code explains what moving from one to the other involves.

Type the number into the data field, choose a format and download the symbol. A barcode is only a drawing of the characters you give it — the generator looks nothing up and allocates nothing — so the right format follows from what the number is:

• A 13-digit product number is an EAN-13 barcode; type the first 12 digits and the check digit is added.
• A 12-digit UPC is a UPC-A barcode, and its compressed eight-digit form is a UPC-E barcode.
• An 8-digit retail number for a small pack is an EAN-8 barcode.
• A 14-digit case number (GTIN-14) belongs in an ITF-14 barcode.
• Any other number — an order, invoice, serial or asset number — goes into a Code 128 barcode, which packs digits two per character. A closed numeric system with even-length numbers can also use Interleaved 2 of 5.

To print the bars without the number underneath, untick Print the human-readable text under the symbol. Keep the digits on EAN and UPC symbols for retail packaging: the GS1 specifications require them, and a till operator types them when a scan fails.

Only some symbologies are alphanumeric. The retail and carton formats carry digits and nothing else, so a letter in the data field produces an error rather than a barcode.

• Code 128: upper and lower case, digits, punctuation and control characters — all of ASCII. Accented letters are outside the standard character set, and most scanners reject or garble them.
• Code 39: upper case A–Z, digits, space and the symbols - . $ / + %.
• Data Matrix, PDF417 and Aztec: any text, including accented letters, and binary data.
• Digits only: EAN-13, EAN-8, UPC-A, UPC-E, ITF-14 and Interleaved 2 of 5.

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. The SVG download is a true vector file — every bar and every digit is a path, not an embedded picture — so it keeps its edges crisp at any size in Illustrator, InDesign, Inkscape or label software, while a PNG scaled up in a layout program produces soft edges that cheap laser scanners misread. The one exception is a symbol with a shape mask, which is exported as an image inside the SVG.

Contrast matters more than colour. Scanners threshold the image, so the bars need to be dark and the background light; black on white is safest, and reversed (light on dark) bars fail on many readers. Avoid red or orange bars in particular: most laser scanners use red light, under which red ink looks as pale as the paper.

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.