Most offices used access badges for granting entrance. These smart cards use Near Field Communication (NFC) to authenticate at the door. Most Android smartphones (since Android 4.4) are nowadays able to emulate these smart cards. At the University of Applied Sciences FHNW, I’ve developed a demonstrator on how to replace these access badges with an app. The setup consisted of a web app managing the access rights and issuing the access tokens. On the other end an offline Raspberry Pi, equipped with an NFC reader and some LEDs to display the door access, emulated a door reader. The Android app stored the access token on the device and could hence authenticate at the door even being offline. The project later evolved into the following paper: Secure Physical Access with NFC-enabled Smartphones