It's a good practice to use separate email addressee for different activities. Tutanota is recommended email provider for now. More information can be found in corresponding services section.
XMPP is the fast, reliable federative standard for messaging, the #1 messenger for black hat hackers. Recommended clients to use:
- GUI: Gajim, Pidgin, Psi, Psi+
- TUI: Profanity
Android: Conversations, Pix-Art, aTalk, Conversations Legacy. Quicksy app can be used to sign up with your phone number like in WhatsApp.
Always use OMEMO encryption unless you trust the servers.
Good full-featured XMPP servers:
Well-polished end-to-end encrypted private messenger with WhatsApp-like experience. Desktop version is very minimal. Amount of collected data and metadata is bare minimum.
Wire is private messenger with modern UI for all platforms. Multidevice, end-to-end encrypted, fully functional without phone, very high-quality audio and video calls.
Free and opensource federative messenger with optional end-to-end encryption and bridges to other networks (Telegram, Discord, IRC, Slack). Very good application for public groups. Please don't use official matrix.org server as it's laggy and was hacked few times. The best possible Discord replacement for now. Take a look here and there to learn more about bridges.
PGP-based messenger for all platforms with bots, rooms and free cloud storage. Uses identity proofs so a lot of medatata is publicly available.
Chat over email, with end-to-end encryption when possible. The best way to chat with those who don't want to install private messaging apps. Can't be used with Tutanota or Protonmail, use it with a traditional Email provider (take a look at corresponding services section).
Not recommended for use.
Collects a lot of data, not end-to-end encrypted by default, Use FOSS or Web version when possible. This messenger can be useful as there are many good chats, bots and channels. It's possible to sign up and use Telegram directly from Riot.im
Viber, WhatsApp, etc
Not recommended for use.
Both are insecure. Both messengers and E2E encrypted but they force you to share your chat history with Google and collect a lot of metadata, WhatsApp has built-in backdoor and Viber can remotely disable end-to-end encryption. If you need to use them, use XPrivacyLua, Shelter and minimize permission. Never agree to back up your data to cloud. If you use Viber utilize Secret Chats, select your age as "under 16", regulary delete your data, never share your contacts with this services. Consider using Oversec for additional encryption.
It looks and feels like Discord. Push-To-Talk can be implemented with HGPTT or Mumble widget can be added to the room instead.