The site of the encrypted messaging app Signal could not be reached in China Tuesday morning.
China’s cyber authorities have become increasingly strict in recent years, which has led to the expansion of applications, media and social media sites banned in the country.
China bans many foreign apps and services, including those from Facebook and Google, but Signal was not previously blocked by the so-called Great Firewall.
The app was still available via the Apple App Store in China as of Tuesday morning, and the app and website appeared to be operating normally in Hong Kong.
The app was not available on third-party Android stores in China, where Google services are largely blocked.
On several occasions, the encrypted messaging app Signal previously stopped working in China without a VPN without giving a reason.
Signal saw an increase in downloads around the world after January 6 when WhatsApp updated its privacy terms, while reserving the right to share user data, including location and phone number, with its parent company, Facebook, and other companies, such as Instagram and Messenger. .
Signal has been downloaded nearly 510,000 times via iOS in China, and 100 million times worldwide via the App Store and Google Play combined, according to data company Sensor Tower.
Signal is relatively young in China, but it has provided a rare way to send encrypted messages over a foreign platform without a VPN.
Tencent’s WeChat mobile app, the dominant messaging app in China with payment functions and other services, has more than 1 billion users globally.
Signal claims to be end-to-end encrypted, which means that the company itself or any outside party cannot display the contents of the messages between the sender and the intended recipient, and this also means that the authorities cannot snoop on the messages.