1. Keybase (2014). https://keybase.io/docs/server_security
2. Perspective API (2017). https://www.perspectiveapi.com/
3. Mastodon social network (2018). https://joinmastodon.org/
4. Matrix: an open network for secure, decentralized communication (2018). https://matrix.org/
5. Sealed sender represents 80% of signal traffic (2019). https://twitter.com/signalapp/status/1075918894521495552