How Psiphon circumvents blocks or censors Psiphon 1.X is no longer supported by Psiphon, Inc.

1.0 – The original home-based server software (released by the Citizen Lab in 2004, rewritten and launched in 2006).

2.0 – A cloud-based secure proxy system.

3.0 – A cloud-based run-time tunneling system.

Psiphon currently consists of three separate but related open-source software projects: and the Citizen Lab at the Munk School of Global Affairs, University of Toronto occasionally collaborate on research projects, through the Psi-Lab partnership. was established as an independent Ontario corporation that develops advanced censorship circumvention systems and technologies. The original concept for Psiphon (1.0) was developed by the Citizen Lab at the University of Toronto, building upon previous generations of web proxy software systems, such as the 'Safe Web' and 'Anonymizer' systems. The codebase is developed and maintained by Psiphon, Inc., which operates systems and technologies designed to assist Internet users to securely bypass the content-filtering systems used by governments to impose censorship of the Internet.

Psiphon is specifically designed to support users in countries considered to be 'enemies of the Internet'. Psiphon is a centrally managed and geographically diverse network of thousands of proxy servers, using a performance-oriented, single- and multi-hop routing architecture.

Psiphon is a free and open-source Internet censorship circumvention tool that uses a combination of secure communication and obfuscation technologies, such as a VPN, SSH, and a Web proxy.

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