# Best Barcodes

> Best Barcodes (https://bestbarcodes.com) is a free, 100% client-side web application for generating vector barcodes and arranging them into millimeter-calibrated label sheets (compatible with Avery®, Uline®, and generic unbranded label sheets) from CSV and Excel spreadsheets.

Best Barcodes solves the common printer alignment problem with pre-cut adhesive label sheets (such as Avery 6870, 5160, 5195, 5163, 5167, and Uline S-21844, S-5042, S-21929, S-3845, S-15183). When printing labels from desktop software or standard PDF generators, printer feed tolerances often cause barcodes or product names to shift across the physical label boundaries. Best Barcodes runs entirely in the user's browser, provides real-time millimeter and inch micro-calibration of global page margins and inner-label translation offsets, and generates print-ready sheets for instant browser printing or high-resolution PDF download.

## Key Capabilities

- **Spreadsheet Parsing & Batch Modes**: Direct in-browser parsing of `.csv`, `.xlsx`, `.xls`, `.tsv`, and `.txt` files via PapaParse and SheetJS. Automatically maps Column A to barcode data and Column B to product name / text, skipping header rows. Leading zeros in GTIN/UPC numbers are strictly preserved.
- **Spreadsheet Fill Modes**: User can toggle between "1 Label per Row" (sequential printing) and "Full Page per Row" (each spreadsheet row fills an entire dedicated sheet, e.g. 20 rows = 20 full sheets of 30 or 60 labels).
- **Single & Manual Entry**: Users can also type or paste individual barcode numbers and descriptions with 1-click sheet generation or list appending.
- **GS1 Retail Compliance**: Native wrapped 1-5-5-1 layout for UPC-A and centered notch layout with tightened outer digit spacing and balanced quiet zones for EAN-13. Guard bars never cut through numbers.
- **Millimeter Micro-Calibration**: Dedicated number inputs bound to dynamic CSS Grid variables (`--page-margin-top`, `--page-margin-left`, `--inner-offset-x`, `--inner-offset-y`) allowing physical shifts of printouts by tenths of a millimeter.
- **Dual Export Channels**: Instant vector browser print dialog (`window.print()`) configured with `@page { size: letter; margin: 0; }` and standalone high-resolution 300+ DPI PDF generation via jsPDF.
- **100% Privacy & Security**: Zero backend servers or data telemetry. User spreadsheets and barcode contents never leave the user's local machine.

## Supported Barcode Symbologies

1. **UPC-A (GTIN-12)**: 12-digit standard North American retail barcode with human-readable outside leading and check digits.
2. **EAN-13 (GTIN-13) / ISBN**: 13-digit international retail and book barcode with optimized quiet zones.
3. **Code 128**: Full alphanumeric high-density symbology for inventory, shipping, and serial numbers.
4. **Code 39**: Alphanumeric uppercase symbology for industrial, automotive, and military use.
5. **UPC-E**: Zero-compressed 6-8 digit retail code for small packages.
6. **EAN-8**: 8-digit retail code for small items.
7. **Codabar**: Numeric symbology with start/stop flags for libraries, blood banks, and shipping.
8. **Interleaved 2 of 5 (ITF)**: Numeric-only high-density barcode for logistics and warehousing.
9. **PostNet**: US Postal Service delivery point routing barcode.
10. **QR Code**: 2D matrix barcode for URLs, text, and asset tracking.

## Supported Label Sheet Templates (Avery, Uline & Generic Equivalents)

- **2.25" × 0.75" (Avery 6870 / Uline S-21844)**: 3 columns × 10 rows = 30 labels per US Letter sheet.
- **1.75" × 0.66" (Avery 5195 / Uline S-21929)**: 4 columns × 15 rows = 60 labels per sheet.
- **2.625" × 1.00" (Avery 5160 / Uline S-5042)**: 3 columns × 10 rows = 30 address labels per sheet.
- **4.00" × 2.00" (Avery 5163 / Uline S-3845)**: 2 columns × 5 rows = 10 shipping labels per sheet.
- **1.75" × 0.50" (Avery 5167 / Uline S-15183)**: 4 columns × 20 rows = 80 micro labels per sheet (also fits Uline S-16988, S-17379).
- **4.00" × 1.00" (Avery 5161 / Uline S-5044)**: 2 columns × 10 rows = 20 wide address labels per sheet.
- **Custom Sheet Dimensions**: User-defined grid columns, rows, margins, and label dimensions.

## Documentation & Machine-Readable Resources

- [Full Architecture & API Reference](https://bestbarcodes.com/llms-full.txt): Complete in-depth specification for agents and developers, including CSS grid math, URL hash preset schemas, and GS1 layout algorithms.
- [Clean Markdown Mirror](https://bestbarcodes.com/index.md): Markdown mirror of the application interface, user guides, and troubleshooting steps.
- [XML Sitemap](https://bestbarcodes.com/sitemap.xml): Search engine and crawler index sitemap.
- [Sample CSV Template](https://bestbarcodes.com/sample-data/sample-barcodes.csv): Ready-to-use two-column spreadsheet template with 30 sample items.

## Optional

- [GS1 General Specifications](https://www.gs1.org/standards/barcodes-epcrfid-id-keys/gs1-general-specifications): Official international barcode sizing and quiet zone guidelines.
- [bwip-js Barcode Engine](https://github.com/metafloor/bwip-js): JavaScript translation of Barcode Writer in Pure PostScript used for vector barcode generation.