WhatsApp is gaining huge popularity in the highly competitive instant messaging platform. The standalone company has achieved a new milestone of 400 million active monthly users, with more than 100 million added in the last four months.

WhatsApp is now as popular as any instant messaging service or any social network. Millions of people use the app to share messages, pictures, videos, locations, contacts and more in a simple and fast way. The instant messenger has achieved yet another milestone-400 million active monthly users. This number counts only those users who access the service at least once a month, which means the registered user-base is much more than 400 million.

WhatsApp, founded by Brian Acton and Jan Koum in 2009, is a multi-platform messaging service. The company boasts uninterrupted service without any advertisements. The service competes directly with other chat companies, such as SnapChat, Line, iMessage, BBM and more. The app gets a marvel 4.5-star rating out of 5 stars on Google Play Store.

WhatsApp's popularity can be analyzed by its rapid growth. The new milestone was achieved mainly by the sudden increase in its user-base. More than 100 million active users were added in the last four months, that's 350 million users in October and 300 million in August. This means the app is offering everything a user is looking for in an instant messaging service.

"Today, we're proud to announce that because of you, WhatsApp has reached a milestone that no other mobile messaging service has achieved: 400 million monthly active users, with 100 million active users added in the last four months alone. This isn't a count of people who just registered for WhatsApp - it's the number of people who are actively using the service every single month," WhatsApp CEO Jan Koum wrote in the company's blog, Thursday.

WhatsApp delivers 16 billion messages per day, receives about 32 billion messages and nearly 500 million images are sent per day by users on the service, according to AllThingsD. The company is run by a small team of 50 engineers who solely focus on delivering the best user experience.