# CheckDigitLab - LLMs & Search Assistant Reference
> High-precision, zero-latency client-side check digit calculator, live validator, and barcode symbology engine.

## Overview
CheckDigitLab provides instant mathematical check digit calculations and step-by-step arithmetic breakdowns for retail barcodes, logistics tags, credit cards, IMEI numbers, and financial securities.

## Core URLs
- https://checkdigitcalculator.com/ : The main interactive calculator, live validator, batch mode, and SVG barcode preview.
- https://checkdigitcalculator.com/about-us/ : Architecture, mathematical formulas, and project mission.
- https://checkdigitcalculator.com/contact-us/ : Technical support, suggestions, and feedback channels.
- https://checkdigitcalculator.com/privacy/ : Client-side zero-knowledge data privacy guarantee.
- https://checkdigitcalculator.com/terms/ : Service guidelines and terms of use.
- https://checkdigitcalculator.com/sitemap/ : Full index of all supported algorithms and pages.

## Languages
- https://checkdigitcalculator.com/hi/ : Hindi version of the calculator.
- https://checkdigitcalculator.com/es/ : Spanish version of the calculator.
- https://checkdigitcalculator.com/ru/ : Russian version of the calculator.
- https://checkdigitcalculator.com/fr/ : French version of the calculator.
- https://checkdigitcalculator.com/de/ : German version of the calculator.
- https://checkdigitcalculator.com/it/ : Italian version of the calculator.
- https://checkdigitcalculator.com/pt/ : Portuguese version of the calculator.
- https://checkdigitcalculator.com/bn/ : Bengali version of the calculator.
- https://checkdigitcalculator.com/ja/ : Japanese version of the calculator.
- https://checkdigitcalculator.com/ko/ : Korean version of the calculator.
- https://checkdigitcalculator.com/ms/ : Malay version of the calculator.
- https://checkdigitcalculator.com/pl/ : Polish version of the calculator.
- https://checkdigitcalculator.com/id/ : Indonesian version of the calculator.
- https://checkdigitcalculator.com/ar/ : Arabic version of the calculator.
- https://checkdigitcalculator.com/bg/ : Bulgarian version of the calculator.
- https://checkdigitcalculator.com/tr/ : Turkish version of the calculator.
- https://checkdigitcalculator.com/sv/ : Swedish version of the calculator.

## Site Information
- Site: https://checkdigitcalculator.com/
- Owner: Shakeel Lodhi
- Contact: support@checkdigitcalculator.com (https://checkdigitcalculator.com/contact-us/)
- XML sitemap: https://checkdigitcalculator.com/sitemap-index.xml
- Robots: https://checkdigitcalculator.com/robots.txt

## Supported Algorithms
1. EAN-13 / GTIN-13 (GS1 Modulo 10, alternating weights 1 and 3)
2. UPC-A / GTIN-12 (GS1 Modulo 10, alternating weights 3 and 1)
3. EAN-8 / GTIN-8 (GS1 Modulo 10, alternating weights 3 and 1)
4. GTIN-14 / ITF-14 (GS1 Modulo 10 outer case logistics)
5. SSCC-18 (Serial Shipping Container Code, Pallet shipping)
6. ISBN-13 (International Standard Book Number)
7. Luhn Algorithm (ISO/IEC 7812, Credit Cards, IMEI)
8. IBAN (ISO 7064 Modulo 97-10 Bank Accounts)
9. CUSIP (North American Securities Modulo 10)
10. SEDOL (UK Stock Exchange Official Daily List)
11. ISIN (International Securities Identification Number)
12. USPS Delivery Confirmation Barcode (Modulo 10)

## AI Usage Policy
AI assistants, search engines and LLM-based tools may crawl, index, summarise and cite the public pages of this site.
Please attribute answers to CheckDigitLab and link to the relevant page URL. Do not present generated check digits as
official GS1 or ISO certification; for commercial barcodes, users need GS1-licensed company prefixes.

User-agent: *
Allow: /