Magspoof

https://github.com/samyk/magspoof

MagSpoof - credit card/magstripe spoofer
Allows you to store all of your credit cards and magstripes in one device
Works on traditional magstripe readers wirelessly (no NFC/RFID required)
Can disable Chip-and-PIN (code not included)
Correctly predicts Amex credit card numbers + expirations from previous card number (code not included)
Supports all three magnetic stripe tracks, and even supports Track 1+2 simultaneously
Easy to build using Arduino or other common parts
MagSpoof is a device that can spoof/emulate any magnetic stripe or credit card. It can work "wirelessly", even on standard magstripe/credit card readers, by generating a strong electromagnetic field that emulates a traditional magnetic stripe card.

Note: MagSpoof does not enable you to use credit cards that you are not legally authorized to use. The Chip-and-PIN and Amex information is not implemented and using MagSpoof requires you to have/own the magstripes that you wish to emulate. Simply having a credit card number and expiration is not enough to perform transactions. MagSpoof does allow you to perform research in other areas of magstripes, microcontrollers, and electromagnetism, as well as learn about and create your own devices similar to other existing, commercial technologies such as Samsung MST and Coin.

https://camo.githubusercontent.com/d19315a0e0a502aba7686f16ed7336ea14b4…

How MagSpoof Works
MagSpoof emulates a magnetic stripe by quickly changing the polarization of an electromagnet, producing a magnetic field similar to that of a normal magnetic stripe as if it's being swiped. What's incredible is that the magstripe reader requires no form of wireless receiver, NFC, or RFID -- MagSpoof works wirelessly, even with standard magstripe readers. The stronger the electromagnet, the further away you can use it (a few inches in its current iteration).

MagSpoof also uses inexpensive, off the shelf parts (described in the Hardware section), and can be built with almost nothing more than an Arduino, wire and a battery! I use a motor driver to provide a reasonable amount of power.

Normally electromagnets have an iron core, however we lose the core for the sake of space and portability. Also, while the iron core does make the electromagnet more efficient, we still produce more than enough power to work.

MagSpoof improves on new cards such as Coin. I'm a customer of Coin, and while I love their app and the card, the card actually works a very small percentage of the time. After looking over Coin's FCC docs, I noticed they use two coils to produce a (very small) electromagnetic field, however it's severely deficient and the card works less than 50% of the time for me, sadly.

I found that by emulating a card with MagSpoof, if I send Track 1 one way, and then send Track 2 reversed, every card reader will assume I simply swiped a card back and forth, use the data from both tracks and my strong electromagnet, and properly read all of the data. This is extremely effective, uses only a single coil, and works for both tracks simultaneously. This also allows MagSpoof to work on Track 3.

Additionally, if you're using a Chip card with Coin, you still need to bring your actual credit card to dip, however because MagSpoof can disable Chip-and-PIN (see below), it does not require you to bring your card with you.

I've removed the Chip-and-PIN disabling functionality from MagSpoof.