Leon Böttger's Experimental Firmware Turns Any Espressif ESP32 Into a Google Find My Device Tag
Still in the early stages of development, the custom firmware comes with tools for locating tags on the network too.
Developer and security researcher Leon Böttger has written a firmware that lets any Espressif ESP32 microcontroller act as a device on the Google Find My Device network — along with standalone tools for querying trackers and compatible devices.
"This code enables you to use an ESP32-device as a custom Google Find My Device tracker. Note that the firmware is very experimental," Böttger writes of the project. "The firmware works differently to regular Find My Device trackers. It is made to be as simple as possible. It has no Fast Pair support, MAC rotation, advertisement rotation, etc."
Google launched the Find My Device service in 2013, allowing owners of lost Android smartphones and tablets to locate their devices based on connections to other nearby devices. In 2024 the company expanded the Find My Device network to cover additional devices, including asset tracking tags — and now it's possible to build your own tag on the cheap.
Böttger's firmware, part of a wider project dubbed Google Find My Tools, allows Espressif ESP32 devices to be loaded with a public key and registered on the Find My Device network like any other tag — with a few caveats. The first two are the biggest: at the time of writing tags built using the firmware wouldn't show in Google's Find My Device app but could be located using Böttger's own Python tool, and devices may need to be re-registered to the network after three days in operation. "Working on a fix," Böttger says of the latter.
The project is similar in many ways to OpenHaystack, which turns similarly-specified low-cost microcontrollers into Apple AirTag equivalents compatible with the company's own Find My network — and for which engineer Aaron Christophel recently wrote a web flasher to simplify the process of turning a Telink TLSR8252-based microcontroller module, costing around $2, into a working AirTag clone.
The firmware, along with tools for querying Find My Device compatible hardware, reading out their encryption keys, and decrypted locations sent from the network, is available on GitHub under the reciprocal GNU General Public License 3.
