ZeroNet uses cryptography (Bitcoin library) and BitTorrent DHT (centralized trackers) to build a distributed censorship-resistant network.
Users can publish static or dynamic sites/applications into ZeroNet and visitors can choose to also serve the application/site. Sites /applications will remain on-line even if it is being served by only 1 peer.
When a site/app is updated by its owner, all nodes (including previous visitors) serving that site/app, will receive only the incremental updates done to the site content (and in real time).
Zeronet counts with a built-in SQLite database. This makes content-heavy site development easy. The database is also synced with hosting nodes with incremental updates.
I2P is an anonymizing network, offering a simple layer that identity-sensitive applications can use to securely communicate. All data is wrapped with several layers of encryption, and the network is both distributed and dynamic, with no trusted parties.
Many applications are available that interface with I2P, including mail, peer-peer, IRC chat and others.
Alternative i2p Clients: https://geti2p.net/en/about/alternative-clients
The main I2P client implementation uses Java. If for some reason you can't use Java on your device, there are alternative implementations developed by community members.
i2pd i2pd is a I2P client implementation in C++. As of early 2016, i2pd is became stable enough to be used in production, and since summer 2016 it fully implements all I2P APIs.
Kovri Kovri is active i2pd fork developed for Monero cryptocurrency.
Go-I2P Go-I2P is I2P client developed using the Go programming language. The project is in early development.
IPFS is a global, versioned, peer-to-peer filesystem. It combines ideas from Git, BitTorrent, Kademlia, SFS, and the web. It is like a single bittorrent swarm, exchanging git objects. IPFS provides an interface as simple as the HTTP web, but with permanence built in. You can also mount the world at /ipfs. IPFS could become a new major subsystem of the internet. If built right, it could complement or replace HTTP. It offers two approaches: content-addressing (ipfs://) and uploader-addressing (ipns://) allowing for mutable sites.
Freenet is free software which lets you anonymously share files, browse and publish "freesites" (web sites accessible only through Freenet) and chat on forums, without fear of censorship. Freenet is decentralised to make it less vulnerable to attack, and if used in "darknet" mode, where users only connect to their friends, is very difficult to detect.
GNUnet is a framework for secure peer-to-peer networking that does not use any centralized or otherwise trusted services. A first service implemented on top of the networking layer allows anonymous censorship-resistant file-sharing. Anonymity is provided by making messages originating from a peer indistinguishable from messages that the peer is routing. All peers act as routers and use link-encrypted connections with stable bandwidth utilization to communicate with each other. GNUnet uses a simple, excess-based economic model to allocate resources. Peers in GNUnet monitor each others behavior with respect to resource usage; peers that contribute to the network are rewarded with better service.
Hypercore Protocol is a peer-to-peer data network built on the Hypercore logs. Hypercores are signed, append-only logs. They're like lightweight blockchains without the consensus algorithm. As with BitTorrent, as more people "seed" a dataset it will increase the available bandwidth.
dn42 is a big dynamic VPN, which employs Internet technologies (BGP, whois database, DNS, etc). Participants connect to each other using network tunnels (GRE, OpenVPN, Tinc, IPsec) and exchange routes thanks to the Border Gateway Protocol...
dn42 can be used to learn networking and to connect private networks, such as hackerspaces or community networks. But above all, experimenting with routing in dn42 is fun!
Librevault is an open-source peer-to-peer file synchronization program, designed with convenience and privacy in mind. Our goal is to make a better alternative to BitTorrent Sync and Syncthing.