A card shop is a merchant that sells payment card data. A genuine listing states the BIN, brand, level, country and balance band, says when it was last checked, and publishes a refund or replacement window.

How does card validation work?

A validator checks the structure of a card record: the ISO 7812 data elements, the Luhn check digit, the expiry date and the security code. This is different from an authorisation request, which is sent to the issuer.

A BIN is the first six digits of a payment card. Those six digits identify the issuing bank, brand, card level and country of issue.

What is the difference between CVV and CVC?

The name depends on the brand: Visa calls it CVV2, Mastercard calls it CVC2. Both are 3 digits on the back. AMEX uses a 4-digit CID on the front.

What is an ISO 7812 card record?

An ISO 7812 card record is the set of data elements stored on a payment card: the primary account number, the expiry date, the service code, the discretionary data and the cryptographic checksum.

Track 1 and track 2 are the two record formats defined by ISO/IEC 7813 for the magnetic stripe. They carry the card number, expiry date, service code and, optionally, the cardholder name.

What is a non VBV bin?

A non VBV bin is a card range whose issuer does not enforce 3D Secure during authorisation.

Payment Card Engineering Reference, Tools and Open Data

Q: What is the Luhn algorithm?

The Luhn algorithm (mod 10) is the checksum formula used to validate payment card numbers. It detects single-digit errors and most transpositions.

An independent reference for payment card engineering. Covers how identifiers are allocated (IIN/BIN, PAN), how record formats are structured (ISO/IEC 7812, 7813, EMV TLV), how validation algorithms work (Luhn and related checksums), and how authorisation, settlement and 3-D Secure fit together. Ships 74 client-side tools and an open dataset of 374,788 BIN prefixes. Written and maintained by Marcus Hale.

Last updated: October 20, 2026 · About & editorial standards

Start Here

What Is a BIN?

How the first six digits identify issuer, brand, level and country.

Card Validation

What each validation layer checks, and what it cannot prove.

Glossary

Identifier, record format, authorisation and network terms defined.

Free Tools

BIN lookup, Luhn, EMV TLV, CVV, IBAN, SWIFT and 20 more.

Luhn Algorithm

How card numbers are validated with the mod-10 checksum.

EMV TLV Parser

Decode and build chip data structures in the browser.

BIN Database

374,788 BINs across 225 countries, 20 brands and 860 issuers.

Free BIN API

REST endpoint returning issuer, brand, type and country for any prefix.

Blog

Articles on identifiers, validation, records and card security.

About This Site

Dark Dollars is an independent reference for payment card engineering: identifiers, record formats, validation algorithms, authorisation flows and security standards. Everything is written and reviewed by Marcus Hale, a payment systems analyst with over 12 years of experience across card networks and transaction processing. Every tool runs client-side, and no input ever leaves your browser.

We publish guides, a glossary, original data studies and 74 free client-side tools. We do not sell card data. A disclosed sponsored listing points to the operator's storefront, and nothing else on this site is a commercial link.

Start with the reference

Everything on this site is written for people who need to understand how card data works, not for people who need to be sold to. Start with the identifier and record format references, then use the tools to apply them.

Frequently Asked Questions

What is a BIN and how many are there?

A BIN is the first six digits of a payment card, identifying the issuer, brand, card level and country. This site indexes 374,788 of them across 225 countries and 18,373 issuing banks.

How do I validate a card number?

Check the length against the network rules, verify the Luhn checksum, look up the BIN to confirm issuer and brand, check the security code length and confirm the expiry is inside its validity window. Each check answers a different question.

What is the Luhn algorithm?

The mod-10 checksum used to validate payment card numbers. It doubles every second digit from the right, subtracts 9 from results above 9 and checks the sum is divisible by 10.

What is EMV TLV and why does it matter?

Tag, length, value is how EMV encodes chip data objects. Understanding the structure lets you read a transaction record field by field, which is what the TLV parser on this site does.

What is the difference between CVV, CVC and CID?

The name depends on the network: Visa uses CVV2, Mastercard uses CVC2, American Express uses CID. All are 3 digits except the AMEX CID, which is 4.

What data do you publish?

Identifiers and record structures from the ISO and EMVCo specifications, and an open BIN dataset published under a Creative Commons Attribution 4.0 licence. The full methodology is on the data sources page.

Do the tools send my input anywhere?

No. Every tool runs entirely in your browser. The BIN data is fetched as a static JSON chunk, and nothing you type is transmitted or logged.

Is there an API?

Yes, a free key-less REST API. GET /api/bin/424242 returns the scheme, type, category, issuer and country for any prefix, with an OpenAPI specification published alongside it.

Editorial Standards

Content is written and reviewed by our editorial team. We aim for accuracy on terminology, formats and procedures, and update pages when facts change. Corrections are welcome via the contact page. We do not sell cards on this site; store links are provided for reference only. Read our full editorial standards.

Last updated: October 20, 2026 · Author profile · Contact · Changelog