Facebook-owned messaging service WhatsApp continues to grow at a rapid rate, recently surpassing 800 million active monthly users.

WhatsApp founder and chief executive Jan Koum revealed the new milestone in a new Facebook post where he confirmed these were active monthly users and not registered accounts.

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WhatsApp was at 700 million in the last months of 2014, adding 50 million every one to two months. This rapid growth comes from WhatsApp's popularity in India, Brazil, Mexico and other heavily populated, low-income countries where WhatsApp acts as the perfect messaging service.

Not only has WhatsApp become the most popular messaging platform is these regions, but for some it's the only messaging service. Facebook Messenger takes up too much RAM on low-end mobile devices and WhatsApp is available on older devices like Nokia Symbian, BlackBerry and Android Gingerbread, Ice Cream Sandwich.

Having the service on every platform allows WhatsApp to spread easily throughout these countries where low-end Android and BlackBerry phones dominate the market.

WhatsApp has spent the past year working on security through text and voice encryption, alongside a voice over IP (VoIP) service allowing people to call for free across the world at no extra cost.

Facebook is delegating all of the typical messaging app features to WhatsApp while it continues to build its own platform on Messenger. Announced at the F8 Developer Conference, third-party developers will now be able to build apps over-the-top of Messenger.

That means things like news articles, emojis, videos, GIFs and all other types of media will be available to view inside Messenger instead of clicking a link and diverting to another webpage. Facebook has shown it wants all content -- regardless of where it was originally from -- to be opened inside the social network rather than outside through a link.

WhatsApp's biggest competitors, WeChat and LINE, appear to be taking the Facebook Messenger approach of over-the-top applications inside the messaging service. This may give WhatsApp free roam in the messaging market for users that only want to read messages.

WeChat does have the Chinese market where it holds over 400 million users, but outside of China the results are grim. LINE has around 250 million users but suffers from the fact it's completely unknown outside of Southeast Asia and isn't that popular in China.

TagsWhatsApp, messaging, Facebook Messenger, mobile app