BYTETOOLS

Barcode Generator

Generate Code 128 barcodes online with checksum, adjustable bar width and height, optional text label, and PNG download. Free and fully private.

2
100

The start code, modulo-103 checksum and stop pattern are added automatically. Keep the white quiet zones when printing so scanners can read the code.

What is the Barcode Generator?

The ByteTools Barcode Generator creates industry-standard Code 128 barcodes from any text or number.

  • True Code 128 encoding with automatic checksum
  • Compact Code C mode for even-length numeric values
  • Adjustable bar (module) width and barcode height
  • Optional human-readable text under the bars
  • PNG download with proper quiet zones for reliable scanning
  • Validates input — warns about characters Code 128 cannot encode

How to use the Barcode Generator

  1. 1

    Type the text or number to encode (printable ASCII characters).

  2. 2

    Adjust bar width and height to suit your label.

  3. 3

    Toggle "Show text below barcode" for a human-readable label.

  4. 4

    Check the live preview, then click Download PNG.

About the Barcode Generator

The ByteTools Barcode Generator creates industry-standard Code 128 barcodes from any text or number. Code 128 is the high-density symbology used on shipping labels, inventory tags, ID badges and logistics documents worldwide — it encodes the full printable ASCII set and switches to a compact numeric mode for digit-only values.

Type your value and the barcode renders instantly, with the mandatory start code, modulo-103 checksum and stop pattern computed automatically. Adjust bar thickness and height for your label size, toggle the human-readable text underneath, and download the finished barcode as a PNG for printing.

Rendering happens on a canvas in your browser — product codes, serial numbers and tracking IDs never leave your device, so the tool is safe for internal inventory data.

Frequently asked questions

What is a Code 128 barcode used for?

Code 128 is the workhorse of logistics: shipping labels (including GS1-128), warehouse bins, asset tags, ID cards and ticketing. It is preferred over Code 39 because it encodes all 128 ASCII characters, packs digits twice as densely, and includes a mandatory checksum.

What characters can Code 128 encode?

Full printable ASCII — letters, digits, punctuation and spaces (character codes 32–126). Accented letters, emoji and other Unicode characters cannot be encoded; this tool flags them so you can correct the value before printing.

Does Code 128 include a check digit?

Yes, always. A modulo-103 checksum character is computed from weighted values of every symbol and placed before the stop pattern. Scanners verify it automatically, which is why Code 128 misreads are extremely rare. This generator adds it for you.

Why does my barcode fail to scan?

The most common causes are missing quiet zones (blank margins at each end), printing too small, or low contrast. Keep the downloaded margins intact, print bars at least 1–2 cm tall, use pure black on white, and avoid resizing the image non-proportionally.

What is the difference between Code 128 and a QR code?

Code 128 is a 1D barcode read by laser and camera scanners, ideal for short IDs in logistics and retail back-office. QR codes are 2D, hold far more data (URLs, Wi-Fi, contact cards) and are aimed at consumer phone cameras. Use Code 128 when your scanner hardware expects 1D.

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