OwnTracks
From Wildsong
I am documenting setting up OwnTracks with Home Assistant.
OwnTracks has a smartphone app, it's open source and free and there is a Home Assistant integration.
OwnTraks supports iBeacons, I will try that out if the app seems worth using.
There is a (dockerized) OwnTracks server called OwnTracks Recorder but I am already running Home Assistant so I am looking at the integration only right now.
I run Mosquitto so I should be able to catch MQTT messages transmitted by the OwnTracks app with almost no more work.
Resources
See https://OwnTracks.org
See also Presence Detection.