Encrypted messaging app Signal is no longer accessible in China, as the Great Firewall caught up with one of the last censorship-free chat apps that could be used in the country.
On Tuesday morning, mainland Chinese users of the app said they were unable to get the app connected to the internet, a sign that Chinese internet authorities have blocked the service. The app remains accessible in Hong Kong, a special administrative region where the internet is not regulated by Beijing.
Signal’s website was also blocked in China on Tuesday, according to censorship tracking site Greatfire.org.
Signal did not immediately respond to a request for comment. The spokesperson at the Cyberspace Administration of China could not be reached for comment.
In China, social media apps have to comply with the government’s requirements to censor speech deemed sensitive and conduct surveillance on users. Users of WeChat, the top messaging apps in China, have been punished for what they said in private chat rooms.
Most foreign chat apps, including WhatsApp, Telegram, and Messenger, are only accessible in China with a virtual private network (VPN).
Signal was one of the last ones that had survived after its 2014 release, until now. Although the app is far from becoming a mainstream platform like WeChat, it has provided a refuge for some activists, journalists, and other tech-savvy users who wish to have secure communications.
The app had been downloaded about 510,000 times on the Apple app store in China, according to Reuters, citing data from Sensor Tower.
For now, iMessage and FaceTime, which Apple says are end-to-end encrypted, are still allowed in China.
In February, the Chinese government blocked Clubhouse, after Chinese users flocked to the audio chat app to talk about political topics such as the Tiananmen crackdown and the internment camps in Xinjiang.
Some foreign social platforms, such as LinkedIn, have chosen to censor its content in order to operate in mainland China. LinkedIn recently suspended new user registration in China without explaining why. The company said on March 9 it was working “to ensure we remain in compliance with local law.”
Follow Viola Zhou on Twitter.