I have built a chat app called FreeTime!
I got tired of every chat app either selling my data, requiring my phone number, or bombarding me with ads. So I built FreeTime an Android messenger that does none of that.
It's fully open source on GitHub with the APK ready to download. Messages are real-time with read receipts and typing indicators, all your media is end-to-end encrypted so even I can't see what you send, and there's zero data collection. No phone number required to sign up, no contacts uploaded to a server, no analytics SDKs phoning home. You can create groups, set up channels with permissions, and use two-factor authentication if you want the extra security. Voice and video calls are coming in the next update.
Building it was kinda hard since i was still new with android studio, kotlin and gradle, but after all the project come out good. Getting the encryption right was straightforward AES-256 per file, keys encrypted to each recipient but making it feel fast while doing all that crypto in the background took real effort. Also all the project was made to be self-hosted and controlled form a simplified admin pannel running locally on the master-server to facilitate admins work. The infrastructure was made with the intent to self host the master-server and some peer servers on my local machines (like i'm doing right now) and maybe using also an hosting plan in the future.
Would love for people to try it, break it, and tell me what sucks. The whole point of putting it on GitHub is to be transparent and letting the others see how i have made it, even if it is still the first version and is still a little rough. Here's the link to the github project:
Github --> https://github.com/coderguy787/FreeTime