WeChat, What's App, and Line are the three messaging App giants in terms of number of users. What's App has 450 million users and Facebook just paid to acquire it. A technology critic Yu Fu gave positive reviews towards the act by saying “platform is king”.

In addition to Taiwan, Thailand, Japan, India, Indonesia and Spain, the countries that have over 1 million Line registered users now include the United States, South Korea, Malaysia and Mexico.

Daily text messages sent via Line has reached as many as 10 billion, while over 12 million free calls using the system are made a day, the developer said.

Akira Morikawa, Chief Executive Officer of Line Corp., expressed delight at hitting the 400-million-user milestone, and said the company expected to reach 500 million users within 2014 according to an earlier report.

Last but not least, Line is famous for its various stickers, which can be used when texing. Though using Line can make free calls, these stickers are not for free at all.