> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mattildapayments.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Card fingerprints

> A unique hash for every card in our vault

A card fingerprint can be used to seamlessly identify card numbers stored in your vault without the burden of PCI compliance.

Key features of card fingerprints.

* Secure and irreversible fingerprint generation for every card received by our system
* Inclusion of fingerprint values in API responses wherever payment methods are returned, ensuring seamless integration with your system

## Use-cases

There are a few use cases for card fingerprints.

1. Identifying fraud: Because our API does not return the original raw card number back via our API, it's hard to know if a card
   has been used previously in a fraudulent transaction. For example, two transactions with the same masked card number of
   `4111 11** **** 1111` could be the same number or two different numbers.
2. Identifying duplicate cards: Similarly, you could use the card fingerprint to determine if the same card is stored twice for a user
   without needing to see the original number.

## Availability & limitations

A card `fingerprint` is returned for every `payment_method` returned by our API. Fingerprints will be the same for every unique card number used.
Because of this, payments made with Apple Pay, Click to Pay, and some Google Pay will have a different fingerprint than cards filled in by hand by your
customers.