As a shameless self-promotion side-note, I have written https://trackingco.de/ too, which is kinda open-source too, but has a hosted version which is free while it's beta.
But mine is much simpler and has much less features, mostly because storage is not cheap and I wanted to optimize to it.
But mine is much simpler and has much less features, mostly because storage is not cheap and I wanted to optimize to it.