Delta Chat

Free open source end-to-end encrypted messaging system that works through email. This means if you both have Delta apps running you can chat in encrypted mode, but even people without Delta can chat with you through their normal email account. It’s available for Android, iOS, Linux, Mac and Windows.

Fediverse address:
@delta@chaos.social

Snikket

XMPP-based free open federated messenger project. It aims to make XMPP into a more viable alternative to Whatsapp etc by providing consistency in design and terminology, while still maintaining compatibility with other XMPP apps and servers. (It’s a similar plan to how Mastodon made ActivityPub more mainstream while still being compatible with other ActivityPub server types.)

Fediverse address:
@snikket_im@fosstodon.org

WriteFreely

Free open source federated blogging platform. The interface and options are minimalist, with the focus on reading text with as few distractions as possible. It’s part of the Fediverse, so you can follow WriteFreely blogs from Mastodon etc. You can host a WriteFreely server yourself, or sign up on an existing server.

Fediverse address (main):
@writefreely@writing.exchange

Fediverse address (blog):
@writefreely@blog.writefreely.org