15
f-droid website
(f-droid.org)
F-Droid is an installable catalogue of FOSS (Free and Open Source Software) applications for the Android platform. The client makes it easy to browse, install, and keep track of updates on your device.
Matrix space | forum | IRC
It happen in both http and https, but http wold redirect to https wouldn't it?
The cert is letsencrypt, yes. Didn't verify the details, though.