credit-card-type 0.1.0

Detect a credit card brand (Visa, Mastercard, Amex, ...) from a full or partial number, for type-as-you-go payment UIs. A faithful port of Braintree's credit-card-type npm package. Zero dependencies, no_std.
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credit-card-type

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Detect a credit card brand from a full or partial number.

credit-card-type figures out the card brand (Visa, Mastercard, American Express, …) from a card number — including partial numbers, for type-as-you-go detection as the user types. It is not a validation library; it is the building block a payment form uses to show the right brand icon, apply the right spacing, and hint the CVV length.

A faithful Rust port of Braintree's credit-card-type npm package, which has no Rust equivalent.

  • Zero dependencies
  • #![no_std]
  • 14 brands: Visa, Mastercard, American Express, Diners Club, Discover, JCB, UnionPay, Maestro, Mir, Elo, Hiper, Hipercard, Verve, Naranja
  • Differential-tested against the reference credit-card-type implementation

Install

[dependencies]
credit-card-type = "0.1"

Usage

use credit_card_type::credit_card_type;

// A long-enough prefix resolves to a single brand.
let cards = credit_card_type("4111111111111111");
assert_eq!(cards.len(), 1);
assert_eq!(cards[0].type_, "visa");
assert_eq!(cards[0].nice_type, "Visa");
assert_eq!(cards[0].gaps, &[4, 8, 12]);       // "4111 1111 1111 1111"
assert_eq!(cards[0].lengths, &[16, 18, 19]);
assert_eq!(cards[0].code.name, "CVV");
assert_eq!(cards[0].code.size, 3);

// A short, ambiguous prefix returns every candidate (good for live UI feedback).
let ambiguous = credit_card_type("6");
assert!(ambiguous.len() > 1); // Discover, UnionPay, Maestro, Elo, Hiper, Hipercard

// An impossible prefix returns nothing; an empty string returns all brands.
assert!(credit_card_type("9999").is_empty());
assert_eq!(credit_card_type("").len(), 14);

Look up a brand's metadata directly:

use credit_card_type::{get_type_info, brand};

let amex = get_type_info(brand::AMERICAN_EXPRESS).unwrap();
assert_eq!(amex.gaps, &[4, 10]);   // "3782 822463 10005"
assert_eq!(amex.lengths, &[15]);
assert_eq!(amex.code.name, "CID");
assert_eq!(amex.code.size, 4);

Returned data

credit_card_type returns a Vec<CardType>, each with:

Field Meaning
type_ code-friendly id, e.g. visa, american-express
nice_type display name, e.g. Visa, American Express
gaps indices to insert spaces when formatting (e.g. [4, 8, 12])
lengths valid total digit lengths
code security-code name and size
match_strength Some(n) once the input is determinate, used to pick the best match

When the input is long enough to identify one brand conclusively, the result has a single entry; otherwise every still-possible brand is returned in a stable order.

Normalize first: strip spaces and separators so the input is digits only.

Note on scope

This port covers detection (credit_card_type and get_type_info). The npm package's runtime customization API (addCard / updateCard / removeCard / changeOrder), which relies on mutable global state, is intentionally omitted.

Contributors ✨

This project follows the all-contributors specification. Contributions of any kind are welcome — code, docs, bug reports, ideas, reviews! See the emoji key for how each contribution is recognized, and open a PR or issue to get involved.

Thanks goes to these wonderful people:

License

Licensed under either of MIT or Apache-2.0 at your option.