Barcode Generator

Code 128 Barcode Generation

This barcode generator converts ASCII text into a Code 128 B symbol and renders the result as SVG. Code 128 stores text as a sequence of narrow and wide bars and spaces, then adds a checksum and stop pattern so compatible scanners can validate the symbol.

Code 128 is useful when one compact barcode must hold more than a short numeric identifier. It is common in shipping labels, warehouse inventory, internal asset tags, document references, and test data. This tool runs in the browser, so input is not uploaded to a server.

Supported Input

Code 128 B covers ASCII character codes 32 through 127. Printable letters, numbers, punctuation, and the DEL character are accepted. Unicode characters such as emoji, accented letters, and non-Latin scripts are rejected because they are outside this symbology subset.

The generated symbol contains:

1. Start Code B
2. One Code 128 value for each input character
3. Modulo-103 checksum
4. Stop pattern

Sizing Options

Option	Effect
Bar height	Changes vertical size of bars
Bar width	Changes width of each narrow module

Increasing bar width makes the barcode wider without changing encoded data. Increasing height can improve readability when the symbol is printed small, but the final result should always be tested with the target scanner and printer.

SVG Output

SVG is a vector format, so bars remain sharp when scaled. Download the markup as barcode.svg, copy it into an HTML document, or place it in a label-generation workflow:

<img src="barcode.svg" alt="Code 128 barcode">

const svg = `<svg xmlns="http://www.w3.org/2000/svg">...</svg>`;
document.querySelector("#label").innerHTML = svg;

from pathlib import Path

Path("barcode.svg").write_text(svg, encoding="utf-8")

Code 128 Compared With Other Formats

Format	Best for	Text support
Code 128	Shipping, logistics, internal labels	ASCII
Code 39	Simple industrial labels	Limited alphanumeric
EAN-13	Retail products	Fixed 13-digit numbers
QR Code	URLs and two-dimensional data	Broad Unicode support

Choose a retail-specific format when a standards body or point-of-sale system requires it. Choose a QR code when the payload needs URLs, Unicode, or substantially more data.

Scanning and Printing Tips

• Preserve a clear quiet area around the symbol.
• Use dark bars on a light, non-reflective background.
• Avoid scaling that makes narrow modules too thin for the printer.
• Test both the downloaded SVG and the final printed label.
• Confirm that the receiving scanner expects Code 128.

This generator is intended for general-purpose symbols and development workflows. Regulated shipping, healthcare, retail, and compliance labels may require additional application identifiers, dimensions, human-readable text, or verification steps.