A Chinese national who helped tens of thousands of citizens jump over China's Great Firewall has been forced to flee to the United States over fears for his family's safety.

Key points: There is a growing appetite for uncensored information from outside mainland China

There is a growing appetite for uncensored information from outside mainland China Zou Chengfeng is also involved with the pro-democracy movement in China

Zou Chengfeng is also involved with the pro-democracy movement in China He has been interrogated several times by public security officers over his activities

Zou Chengfeng, 44, started teaching people how to bypass the Great Firewall, a digital border built by the Chinese Government to control the internet, in 2014.

But as demand for uncensored content grew with the crackdown on internet freedom, he created a free tutorial in 2016 which he shared with netizens who approached him on Chinese messaging app WeChat.

Mr Zou told the ABC it was his belief in democracy that inspired him to take on the project.

"Internet in China is completely an intranet — the content you are able to see is only what the Government allows," he said.

"Chinese people who watch CCTV's 7:00pm news bulletin everyday would think China is such a powerful country.

"But when they get the information from the other side of the Great Firewall, they would learn about the real circumstances around the Chinese economy, and how the rest of the world really perceives China."

In order to help more people, Mr Zou said he shopped second-hand stores to buy mobile phones in every brand and model he could find to ensure his tutorials were compatible with a wide range of devices.

He has shared his tutorial with more than 150,000 people on WeChat in the past year alone.

But Mr Zou's tutorials didn't always attract positive attention. He said he was interrogated several times by Chinese public security officers over his project and involvement with the pro-democracy movement.

"At first they wanted to bribe me … then they started to threaten me," he said.

"They said if you insist on doing this, watch out for your wife and children."

Mr Zou, who chose not to elaborate on the movement's activities, said his house in China's south-eastern Jiangxi province had also been raided earlier this year.

"I can't disclose too much information at this stage, because it concerns the safety of others," he said.

"I have escaped from this cage, but most of them are still [on the other side of] the wall."

Jiangxi's Provincial Public Security Department did not respond to a request for comment.

Fearing for the safety of his wife and two children, Mr Zou eventually decided to travel to the United States — where he is seeking political asylum — about four months ago.

He continues to share his tutorials with people in China and hopes to help as many people as possible.

'Most sophisticated online censorship operation in the world'

Amnesty volunteers place cardboard bricks into a symbolic firewall during a protest in Sydney. ( Reuters: Will Burgess, file )

Since the 1990s, the Chinese Government has developed online censorship policies and technological fixes to closely monitor and manage its citizens' access to information.

Consequently, the Chinese people used technologies, such as virtual private networks (VPNs), to climb over the Great Firewall and access sites that were blocked by the Government.

After President Xi Jinping assumed power, the Chinese Government devoted more resources to control online content and began to crack down on VPNs.

Mr Zou's tutorials began training Chinese users in alternative encrypted proxy projects such as Shadowsocks and ShadowsocksR (SSR).

"Because the Communist Party of China keeps changing course in how it blocks the information network, I try to find more convenient ways to climb over the wall," Mr Zou said.

Mr Xi's Government can now track VPN usage — widely used by citizens to access blocked sites. ( Reuters/stringer )

Dynamic Internet Technology (DIT) Chief Executive Officer Bill Xia said China has the most advanced censorship technologies, with "large-scale monitoring powered by artificial intelligence".

DIT developed a software application known as Freegate — a software associated with controversial Falun Gong practitioners and partly funded by the US government — that has enabled users from China to access blocked websites through a range of proxies called Dynaweb.

According to Mr Xia, Freegate and Ultrasurf (another software that enables users to bypass internet censorship) have been widely used in China despite efforts by the Government to block them.

In the Guardian's adaptation of the book, The Third Revolution: Xi Jinping and the New Chinese State, Elizabeth C Economy described Mr Xi's China as having "the largest and most sophisticated online censorship operation in the world".

She noted that Mr Xi set out his vision for the future of China's internet during the opening ceremony of the Second World Internet Conference in Wuzhen city in the eastern Zhejiang province in 2015.

"We should respect the right of individual countries to independently choose their own path of cyber development," Mr Xi said in his opening speech.

"No country should pursue cyber hegemony, interference in other countries' internal affairs or engage in, connive at or support cyber activities that undermine other countries' national security."

China has often claimed that its internet is fully open, but maintained its right to act to secure its "cyber sovereignty".