OpenHaystack allows you to track personal Bluetooth devices using Apple's huge Find My network. It can be used to create your own tracking tags, which you can attach to physical objects (keyrings and backpacks, ...)) or integrate into other Bluetooth-capable devices, such as notebooks.
OpenHaystack allows you to create accessories that can be tracked by Apple's Find My Network. All you need to do is use a Mac and a BBC Micro:bit or other Bluetooth-capable device. The app allows you to track your accessories from anywhere on the planet, even if there is no cellular coverage. Nearby iPhones can locate your accessories and upload them to Apple's servers if they have an internet connection.