Element is an opensource interoperable app running on Web, iOS and Android. It is built around chat rooms, both public and private and provides messaging, filesharing, voice and video conferencing (beta on Android and web), integrations to tools like GitHub, Jira, Jenkins and much more soon. Element is built on the Matrix.org open standard which provides bridges to other systems such as Slack, IRC and a lot more soon.
- It also has chat rooms which can be combined into groups (like Discords servers) and group voice calls. It's open source and can be hosted on an own server or used on one of many free servers.
- FOSS, end-to-end encryption, beautiful interface, easy to set up, fast, responsive. Not bloated like Discord, not a privacy hazard like Discord. You can host your own server. Frequently updated. Supports gifs, videos, emoticons, etc. Clean sound.
- Decentralized, end-to-end encrypted, and easy to use. Excellent client for creating a voice chat room for gaming. Of all the alternatives here, this one most closely mirrors Discord (while not infringing on your privacy).