OB Barcode Generator | Professional Label Tools

Q: What is a Code 128 barcode?

Code 128 is a high-density linear barcode that encodes all 128 ASCII characters — letters, digits, and symbols. It is the global standard for shipping labels and warehouse management systems, offering the highest data density of any linear symbology. In numeric-only mode (Code C sub-set), it doubles capacity by encoding two digits per bar module, making it the most efficient linear format for numeric tracking identifiers.

Q: How much data can a Code 128 barcode hold?

Code 128 supports variable-length data and encodes the full 128-character ASCII set with no fixed upper character limit. In practice, very long strings reduce scanning reliability on lower-end cameras. For numeric-only data, the Code C compression sub-set encodes two digits per symbol, effectively doubling capacity versus other linear barcode formats. It outperforms Code 39 for alphanumeric data density.

Q: How do I generate multiple barcodes at once?

Use the Batch Labels section. Upload a CSV file or paste rows in the format 'format,data' — for example: CODE128,ITEM-00123 or QR,https://example.com. After clicking Generate Sheet, a print-ready label layout appears. Set label width and height in millimeters using the W and H fields, then print directly from the browser or download all labels as a ZIP archive of individual PNG files.

Format Guide & FAQ

Everything you need to choose the right barcode and get it scanning reliably.

Supported Formats

QR Code — best for web URLs, Wi-Fi credentials, and contact cards. Built-in error correction keeps it scannable even when partly damaged.
Code 128 — high-density linear barcode for alphanumeric warehouse IDs and shipping labels; the global standard for logistics.
EAN-13 / UPC-A — standard retail point-of-sale formats issued under a GS1 company prefix.
Code 39 — a legacy format still used by older industrial and military scanners.

Why Client-Side Processing?

Complete privacy: tracking URLs and sensitive IDs never leave your device for rendering.
Speed: render hundreds of scalable SVGs instantly without network delays.
Offline capable: install the app and keep generating without an internet connection.

Pro Scan Tips

High contrast: black bars on a white background ensure reliable reads across laser guns, CCD scanners, and smartphone cameras.
Quiet zone: keep a clear margin — at least 10× the narrowest bar width for linear codes; 4 modules on all sides for QR Codes.
Minimum size: print Code 128 at least 20 mm wide; QR Codes at least 25 × 25 mm for reliable smartphone scanning.
Test before printing: always verify scans on multiple device types before a full print run.

Frequently Asked Questions

What is a Code 128 barcode?

Code 128 is a high-density linear barcode format widely used for logistics, inventory, and internal tracking labels.

How much data can a Code 128 barcode hold?

Capacity varies by scanner and print quality, but Code 128 can hold full ASCII data and is efficient for alphanumeric identifiers.

How do I generate multiple barcodes at once?

Use the Batch Labels section. Upload a CSV file or paste your data, then click "Generate Sheet" to arrange them for printing.

Can I generate barcodes programmatically?

This app is browser-based. For automation, you can use similar barcode libraries (like JsBarcode) in your own server-side or client-side applications.

Is my data uploaded anywhere?

No. All barcode generation runs entirely in your browser. Your data is never transmitted to any server.

Need additional help?

Visit our Support page for detailed troubleshooting and setup guidance.

About OB Barcode Generator

OB Barcode Generator is a free, professional-grade utility for generating high-quality vector and raster barcodes entirely in your browser, built by Molave Labs. For more on how it works and the team behind it, visit the About page.

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