Delta Chat
Version: 1.42.2 Web: https://delta.chat
There’s no dearth of instant messengers; some focus on convenience and interoperability, while others focus on privacy. Delta Chat’s USP is that it doesn’t use a centralised server to exchange messages. Instead, it uses email to send and receive encrypted messages.
The app has RPM and DEB packages, but the most convenient installation is via distro-agnostic Flatpaks and AppImages. Either grab the AppImage from its website or install the app from Flathub with flatpak install flathub chat.delta.desktop .
When you first launch Delta Chat, you must log in to your email account, like hooking up your email with an email client. For known email providers such as Gmail, Fastmail and such, the app can automatically fill in settings. If you’re using an exotic service or running your own server, you must enter its settings manually. You also need to create an app-specific password to let the email provider know that Delta Chat isn’t a bot. The process for doing this differs based on the email provider, and the app points you to the relevant documentation. Once you have the app-specific password, you have to use it along with your email address to log into Delta Chat.
Once you’ve got past the hurdle of logging in, the rest is easy. The app looks and behaves like any chat app. Since it just uses email, you can add friends by their email address. Click on the big + icon to either enter an address manually or browse through your address book to add an existing contact.
You can then converse with them as you do in any IM. To your contacts, the conversation appears like regular emails, which they can respond to. And for you, they appear like conversations in any IM client.