Chime

Chime is a free, open source messenger for Android (GPL-3.0). There's no account and no phone number: your identity is a key that lives on your phone. Messages are end-to-end encrypted, with a post-quantum layer on top, and when the internet goes down they keep moving over Bluetooth, local WiFi, or hotspot, hopping between nearby phones until they arrive.

It's in public beta, and it will always be free.

Why donations

Chime is independently built and funded. There's no company behind it, no investors, no ads, and no plans for any of those: the whole point is that nobody in the middle owns your conversations, and that includes not being owned by a business model that needs to watch you.

That independence has running costs: the relay server that helps phones find each other, hosting, and the domain. Donations cover those first. Beyond that, they fund research and development time.