Wikipedia
UltraSurf is a freeware Internet censorship circumvention product created by UltraReach Internet Corporation. The software enables its users to bypass Internet censorship and firewalls using an HTTP proxy server, and employs encryption protocols for privacy.
The software was developed by Chinese dissidents as a means of allowing internet users to bypass the Great Firewall of China. It currently boasts as many as 11 million users worldwide. The tool has been lauded as "one of the most important free-speech tools on the Internet" by Wired, and as the "best performing" circumvention tool by Harvard University in a 2007 study; a 2011 study by Freedom House ranked it fourth. Critics in the open source community have expressed concern about the software's closed-source nature and alleged security through obscurity design; UltraReach says their security considerations mean they prefer third party expert review to open source review.