WhatsApp, the messaging app acquired by Facebook for $22 billion last year, now has 700 million monthly active users, according to a post by the company’s CEO on Facebook.

Jan Koum also noted that users send more than 30 billion messages per day on the service.

The last official user figure for the messaging service was 500 million, revealed on the company’s blog in April last year.

The latest figure puts WhatsApp a long way ahead of its main rivals and suggests that Facebook CEO Mark Zuckerberg’s ambition to secure several billion users may be realistic.

Facebook’s own Messenger app reached 500 million monthly active users in November, after users were forced to download the standalone version after the functionality was removed from the main Facebook app.

Together with WhatsApp, this means Facebook has a total of 1.2 billion active users across its mobile messaging services. However, there is likely to be a degree of crossover between the two user bases.

In October Zuckerberg outlined Facebook’s plans to ramp up efforts around its mobile apps to make them into successful standalone businesses.

The Facebook CEO said the company believes WhatsApp and Instagram (acquired for $1 billion in 2012) are on the way to reaching one billion people within five years, a scale at which they will become “meaningful businesses in their own right”.

In terms of active users, Tencent’s WeChat (known as Weixin in China) is the closest rival to the two Facebook services. In August the Chinese web company said its messaging app had 438 million monthly active users.

Of the other big names in the messaging app space, Viber revealed in November that it has 209 million active users, while Japan-based LINE said it had 170 million monthly active users in October.

Both players are putting a lot of effort into growing their active user base with the addition of new services to their platforms.