Teamtype enables real-time peer-to-peer collaborative editing of local files using your own text editor or other tools. For example, you can use it for pair programming sessions, brainstorming, or note-taking. It's the missing real-time complement to Git and other version control systems!

• GitHub - teamtype/teamtype: Peer-to-peer, editor-agnostic collaborative editing of local text files. · GitHub

PeerTube is a software that you install on a web server. It allows you to create a video hosting website, so create your "homemade YouTube".
The difference to YouTube is that it's not intended to create a huge platform centralizing videos from the whole world on a single server farm (which is horribly expensive).

On the contrary, PeerTube's concept is to create a network of multiple small interconnected video hosting providers.

• Otr.to - p2p chat, that mean you communicate directly, no logs saved on server
• Otr.to absolutely anonymous, registration free
• Otr.to browser based, that mean you don't need to install or ask somebody to install software
• Otr.to use OTR (Off-the-Record Messaging) - most secure cryptographic protocol
• Otr.to Open-source and written in JavaScript, that mean you can check how it works