IPFS

IPFS is a protocol that combines the features of Bittorrent, CDNs, and deduplication.

Matrix

Matrix is a federated chat protocol that allows users on different servers to talk to each other.

Rooms are mirrored on each server with a user in them, meaning all servers have to leave a room for it to disappear.

Riot

Riot is a client for Matrix, which runs entirely in the browser and can therefore be hosted on IPFS or simply downloaded and run via file path.

It can also be run as a desktop app.

Mastodon

Mastodon is a federated social media platform similar to Twitter.

Users on an instance can communicate with and follow users on any other instance, as well as any other service using ActivityPub.

Peertube

Peertube is a video hosting platform built on ActivityPub and WebTorrent.

It uses WebTorrent to distribute videos between people watching them -thus taking the load off of the server- and ActivityPub to federate with platforms like Mastodon.

Pixelfed

Pixelfed is a federated Instagram alternative that can also federate with Mastodon and Peertube.

OpenStreetMap

OpenStreetMap (OSM) is an alternative to Google Maps that lets anyone use the map data.

It is built by volunteers, and you can contribute using the StreetComplete app.