nheko is a native client for the Matrix network.

Most of the features you would expect from a chat application are
missing right now but we are getting close to a more feature complete
client. Specifically there is support for:

E2E encryption.
VoIP calls (voice & video).
User registration.
Creating, joining & leaving rooms.
Sending & receiving invites.
Sending & receiving files and emoji (inline widgets for images, audio
and file messages).
Replies with text, images and other media (and actually render them
as inline widgets).
Typing notifications.
Username auto-completion.
Message & mention notifications.
Redacting messages.
Read receipts.
Basic communities support.
Room switcher (ctrl-K).
Light, Dark & System themes.
Creating separate profiles (command line only, use -p name).
D-Bus API to allow integration with third-party plugins (does not
support Windows or macOS).