Freenet

Freenet is a peer-to-peer platform for censorship-resistant communication. It uses a decentralized distributed data store to store information, and has a suite of free software for working with this data store. Both Freenet and some of its associated tools were originally designed by Ian Clarke, who defines Freenet's goal as providing freedom of speech with strong anonymity protection.

Freenet works by storing small encrypted snippets of content distributed on the computers of its users and connecting only through intermediate computers which pass on requests for content and sending them back without knowing the contents of the full file, similar to how routers on the Internet route packets without knowing anything about files—except with caching, a layer of strong encryption, and without reliance on centralized structures. This allows users to publish anonymously or retrieve various kinds of information. Freenet has been under continuous development since 2000.

Since Version 0.7 (2008), it offers two modes of operation: a darknet mode in which it connects only to friends, and an opennet-mode in which it connects to any other Freenet user. Both modes can be used together. When a user changes to pure darknet operation, Freenet becomes very difficult to detect from the outside. The transport layer created for the darknet mode allows communication over restricted routes as commonly found in mesh networks, as long as these connections follow a small-world structure.

The distributed datastore of Freenet is used by many third-party programs and plugins to provide microblogging and media sharing, anonymous, decentralised version tracking, blogging, a generic Web of trust for decentral spam resistance, Shoeshop for using Freenet over Sneakernet and many more.

Freenet has always been free software, but for most of its history it required users to install non-free Java software. In 2011, this problem was solved and Freenet can now also work with the free OpenJDK Java system.