"Telegram Messenger" (Telegram) rose rapidly on the most downloaded apps lists in South Korea after claims that the country's number one multi-platform texting app "Kakao Talk" disclosed user information to the government. This comes after prosecutors vowed to clamp down on negative comments online about South Korean President Park Geun-hye, regarding her whereabouts when the Sewol Ferry sunk in April.
Telegram became the most popular app in South Korea on October 1 when some 610,000 South Koreans dowloaded it. Kakao Talk lost 400,000 users, according to Rankey.com.
"Many people say that the South Korean government is not happy about the criticism, and that is why they are stepping up the censorship and the measures," says a Seoul-based journalist who wishes to remain unnamed.
"People are beginning to worry that their privacy might be breached due to this internet censorship. That is why they are moving to Telegram," he adds.
'Secret Chat' on Telegram
Telegram is so secure that it is considered "unhackable." Its founders, Nicolai and Pavel Durov, have even invited people to try and hack it.
Pavel Durov, co-founder of Telegram Messenger
The two founders reportedly offered anyone who could hack their server $200,000 earlier this year. This competition led several people to take an interest in Telegram.
"The problem with some widely used social messenger sites is that all unencrypted messages can be wiretapped," Rüdiger Weis, IT professor at Beuth University of Applied Sciences in Berlin told DW
Also, the NSA revelations increased awareness about encryption, he notes.
Telegram has the "secret chat" tool which provides more security and offers end-to-end encryption - allowing only the messenger and recipient to read the messages.
"It is almost a magical property of cryptography that strong encryption on normal user devices cannot be broken from the most powerful agencies to the end of our solar system," says Weis.
And just like photo messaging app Snapchat, messages on Telegram can be programmed to self-destruct after a certain amount of time.
Telegram has become so popular that South Koreans are asking for a version in Korean.