ikarus23/mifareclassictool

MIFARE Classic Tool (MCT) is an Android app for working with MIFARE Classic RFID tags. MIFARE Classic is a type of contactless chip found in many keycards, transit cards, and access badges. The app lets you read the data stored on these tags, write new data to them, clone one tag's contents onto another, and inspect or edit the raw data. The core workflow involves keys: MIFARE Classic tags are divided into sectors, and each sector is protected by one or two keys. The app includes a dictionary-based approach where you supply a file of keys you already know, and the app tries each one against each sector to read as much of the tag as it can unlock. It does not crack or brute-force keys it does not already have, and the README is explicit that no key-cracking capability exists or will be added. Beyond reading and writing, the app includes several utility tools: a diff viewer to compare two tag dumps, a decoder for the access condition bytes that control what operations each sector allows, a value block decoder, a BCC calculator, and a display mode that shows raw tag data as readable ASCII alongside the standard hex view. There is also support for external USB NFC readers like the ACR 122U, for cases where the phone's built-in NFC hardware cannot reach a tag. The app is available on Google Play, F-Droid (the open-source Android app store), and as a direct APK download. It is free and open source. The README notes that users need at least basic familiarity with MIFARE Classic technology and should be comfortable reading hexadecimal data, since all input and output is in hex.