But in his free time, he answers to a higher calling: helping his fellow citizens jump the Great Firewall that blocks them from freely accessing China’s internet.

Chen is a volunteer “maintainer” who helps run V2Ray, one of a number of open-source virtual private networks (VPNs) and proxy servers that are gaining in popularity amid China’s crackdown on commercial VPNs, which are illegal to use without government authorisation.

Like commercial offerings such as ExpressVPN and NordVPN, V2Ray, whose original developer is unknown, allows users to avoid censors and mask their internet activity.

But unlike those platforms, free-to-use V2Ray requires some level of technical knowledge to set up and features a range of customisation options.

Chen, whose work includes fixing bugs and monitoring contributions to the project from the open-source community, said more than 141 individuals and groups have added to V2Ray’s source code over the years.

“Trying to house a V2Ray server yourself, you have to understand the technology, that’s why it’s not really popular in other parts of the world right now because there is a learning curve,” Chen, who is based in a European country and asked to be referred to by an alias to conceal his identity, told Al Jazeera.

“It’s not something that people can just open the box and use it. It’s not battery included.”

Despite their relatively steep learning curve, open-source platforms that anonymise internet users are playing an increasingly prominent role in the never-ending cat-and-mouse game between government censors and internet users in China and other undemocratic states.

Global internet freedom declined for the 13th consecutive year in 2023, according to the US-based rights watchdog Freedom House.

China ranked as the most repressive internet environment out of 70 countries assessed by the nonprofit, closely followed by Myanmar, Iran and Cuba.

The rise of artificial intelligence (AI) is also changing how governments censor the internet, according to Freedom House, with at least 22 countries creating legal frameworks encouraging or incentivising tech companies to “deploy machine learning to remove disfavoured political, social and religious speech”.

State-led efforts to control the internet have particular relevance in 2024, a record-breaking year for global elections when voters in more than 50 countries are casting their ballots.

For open internet advocates like Chen, open-source platforms such as V2Ray are attractive in large part because their source code is freely available to the public.

That opens up the platform to scrutiny from anyone concerned about the possibility of it collecting their data or containing secret backdoors that can be accessed by authorities.

“Open source can assure users we are on your side, we are helping you, and everything we do is on behalf of you. We are not trying to help an ISP [internet service] provider or government,” Chen said.

“We are not a spy, and we are helping you. We are representing your interests in a hostile environment.”

While V2Ray is particularly popular in China, it is just one of an array of open-source options available worldwide.

They range from proxy servers, which conceal a user’s IP address, to VPNs that reroute, encrypt and obfuscate internet traffic through a remote server.

Among the best-known platforms is the open-source browser Tor, launched in 2002 to provide anonymity to users online.

Other platforms, such as MTProxy, help users access specific apps like Telegram, the encrypted messaging app.

Browsers Unbounded, a project under development by VPN-like platform Lantern, promises to “crowdsource the internet” by allowing people in countries with an open internet to lend their IP address to those in restrictive environments.

“The idea behind this is that, basically, with Lantern as it exists now, we have about 20,000 IP addresses or so that we rotate through,” Adam Fisk, a lead developer of Lantern, told Al Jazeera.

“And the idea is that, in theory, if we’re able to sort of crowdsource a bunch more IP addresses, in theory, that could be millions of IP addresses that censors have to deal with.”

While the project is still under development, a preliminary version is available as a widget on the news site China Digital Times.

Services like Lantern and V2Ray take advantage of the fact that even in non-democracies such as China, the internet is increasingly indispensable to everyday life.

Since many of these tools are built around anonymity, authorities would need to shut off the internet to prevent their use entirely – a move that is likely to make even illiberal governments squeamish given the enormous disruption and economic damage.

With normal marketing out of the question in repressive environments, platforms like V2Ray often spread by word of mouth, or through “guerrilla-style” advertising.

During internet shutdowns in Iran in 2019, protesters shared information about the popular anti-censorship tool Psiphon via paper flyers distributed at apartment buildings, according to a report by the Carnegie Foundation for International Peace.

The flyers shared information about where to go to download Psiphon, which combines multiple types of technology to obfuscate internet traffic and evade restrictions, as users tried to stay one step ahead of the government.

Tehran, in turn, distributed fake versions of the VPN to spy on protesters, according to research by private cybersecurity company Bitdefender.

Psiphon senior adviser Dirk Rodenburg said the platform’s use rises and falls with global events like protests and elections, sometimes attracting millions of users in a matter of days before dropping back to regular usage levels.

As well as gaining popularity in Iran, the platform has seen widespread use during recent periods of upheaval in Cuba, Myanmar and Russia, Rodenburg said.

“The technologies for detecting and blocking undesirable traffic from the perspective of the censor are getting better, and the techniques for evading are also getting better. So it is a continuous game. We have to stay ahead of them, they have to stay ahead of us,” Rodenburg told Al Jazeera.

“Part of what we do is we partner with university researchers who are in this kind of area to develop protocols that are better at evading censorship strategies.”

Perhaps unsurprisingly, Psiphon has been accused of being backed by the CIA by various governments, including Tehran.

While Psiphon began life as a project at the University of Toronto’s Citizen Lab, it now receives substantial funding from the Open Technology Fund (OTF), a nonprofit funded by the US government.

OTF funds dozens of open-source projects like Psiphon, as well as more experimental tools like the anti-censorship algorithm Geneva, developed by the University of Maryland, which uses machine learning to develop and expand anti-censorship strategies.

OTF said it prefers to fund open-source tools because they are more secure, and can also be independently vetted on the ground by users who might be as wary of the US government as they are of their own.

“Because OTF focuses on populations that are under repressive government surveillance, there is a high bar to gain their trust, and they must be able to independently verify the technologies we support are secure,” Nat Kretchun, senior vice president for programs at OTF, told Al Jazeera.

“Making sure that local, trusted security experts and technologists can independently validate the way a tool works – essentially look under the hood for the kind of things that may put users at risk – is an important part of demonstrating that the tools we support can be trusted and relied upon safely.”