Barcode Generator

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How Barcode Generation Works

This tool uses JsBarcode (an open-source library that wraps the SVG encoding routines for each symbology) to generate barcodes directly in your browser as scalable SVG markup. SVG is the ideal format for barcodes because the resulting image remains crisp at any size, from a 1-inch shelf label to a shipping container decal. When you type a value and pick a format, the script encodes the string into the appropriate pattern of bars and spaces and renders them as filled SVG rectangles on a white background. The download button converts the SVG to a PNG canvas at user-selected resolution so you can use the result in any tool that does not support SVG.

Each symbology has different allowed character sets, fixed lengths, and check-digit rules. EAN-13 requires exactly 13 digits and computes a Mod-10 check digit, so the tool pads short inputs with leading zeros and rejects non-numeric input. CODE-128 supports the full ASCII range including uppercase, lowercase, and control characters, but encodes them with different bar widths. CODE-39 is the classic alphanumeric format used in automotive and military applications. UPC-A is the 12-digit format used on consumer goods in North America. Picking the right format for your use case matters because a barcode scanner that expects EAN-13 will not decode a CODE-128 image, and vice versa.

Frequently Asked Questions

Which barcode format should I pick?

For products sold in retail, use EAN-13 (international) or UPC-A (North America only). For shipping and logistics, use CODE-128 because it encodes the full ASCII set and is what UPS, FedEx, and DHL accept. For internal inventory and warehouse use, CODE-39 is the most universally readable and tolerant of poor print quality. For 2D barcodes that store more data, use the QR Code Generator instead.

What is the difference between SVG and PNG output?

SVG is a vector format that scales to any resolution without losing sharpness, which is ideal for print and for embedding into other documents. PNG is a raster format that is fixed at a chosen pixel resolution, which is what most social-media platforms, email clients, and older label printers expect. This tool outputs SVG natively and lets you download as PNG at 1x, 2x, or 3x resolution for retina-quality displays.

Is there a character limit?

It depends on the format. EAN-13 is fixed at 13 digits, UPC-A at 12 digits, and ITF-14 at 14 digits. CODE-128 can encode up to about 80 ASCII characters before the barcode becomes too wide to fit on a typical label. For longer data, switch to a 2D format like QR Code or Data Matrix.

Are my barcodes private?

Yes. All encoding happens in your browser using the JsBarcode library loaded from a CDN. The text you enter never leaves your device. You can verify this by opening your browser DevTools Network tab while generating a barcode and observing that no POST requests are made.

Why is my barcode not scanning?

Common causes: (1) the bar height is too short — most scanners need at least 10 percent of the bar width in height; (2) the quiet zone (white margin) is missing — leave at least 10 bar widths of empty white space on each side; (3) the file is downscaled to a low-resolution PNG where bars blur together; (4) the printed contrast is poor — use pure black on pure white for maximum reliability.

References and Authority Sources

• Wikipedia — GS1 (the standards body that defines EAN, UPC, and many other retail barcodes)
• Wikipedia — Universal Product Code (the UPC-A format and its 12-digit check-digit calculation)
• Wikipedia — Code 128 (the high-density ASCII format used in shipping)
• JsBarcode on GitHub (the open-source library this tool uses for SVG encoding)