Open source online live tracking server & client

What is the community’s opinion on the software of choice for setting up a tracking server, and have devices report in their locations?
Example devices: Mobile phone (android), car GPS tracker.
Desirable features: Open-source, secure (encrypted) communications between server and client, popular/maintained software, preferably available as an OpenWRT package.

I have never set such a thing up before, if anybody has, we can have a conversation about all the details

I’m interested in how the community thinks how traccar fits the bill.