MTools - Mifare ACR122 PN532 is a free Android app developed by MTools Tec, under the Utilities & Tools category. It is the world's first app that can read and charge your Mifare Classic and Ultralight card directly. Additionally, it can work on NFC, PN53X, and ACR122U. With MTools, you can compare and explore the rules of data, but it is important to know the keys and data rules first.

The app offers several useful functions, including reading and writing to a sector directly, auto-saving keys if they are changed, highlighting display while comparing data, emulate calculate, multi-card, and multi-rules. Additionally, it supports CRC8 and CRC16 calculations. Overall, MTools - Mifare ACR122 PN532 is an excellent app that provides a unique set of features and is a must-have for anyone who needs to work with Mifare Classic and Ultralight cards.