go-credit-card 
Basic credit card validation using the Luhn algorithm
Currently identifies the following credit card companies:
- American Express
- Bankcard
- China Unionpay
- Dankort
- Diners Club Carte Blanche
- Diners Club enRoute
- Diners Club International
- Discover
- InterPayment
- InstaPayment
- JCB
- Maestro
- MasterCard
- Visa
- Visa Electron
Installation
go get github.com/durango/go-credit-card
Quick Start
// Initialize a new card:
card := creditcard.Card{Number: "4242424242424242", Cvv: "11111", Month: "02", Year: "2016"}
// Retrieve the card's method (which credit card company this card belongs to)
err := card.Method() // card.Company({Short: "visa", Long: "Visa"})
// Display last four digits
lastFour, err := card.LastFour() // 4242
// Validate the card's number (without capturing)
err := card.Validate() // will return an error due to not allowing test cards
err := card.Validate(true) // this will work though