At first glance, you might miss the word "monthly" in that title. That's the most relevant word in the title too. Both WhatsApp and Google's gmail have passed 1 billion (with a "B") MONTHLY users. In March of 2015 WhatsApp just passed their 1 billion downloads mark from the Google Play Store. Back in May of 2014, Google's gmail did the same thing.
In less than one year and two years respectively, both apps have converted that threshold into a huge active user base. That means 1/7th of the world's population is actively using both of these apps every single month. This can be seen two ways: one, both of these apps have reached a massive audience, proving they are excellent products, and, two, there is still a long way to go and a ton of people to reach in the world.
Who will come out with the next "killer app" that tops these giants?
Source: WhatsApp, Gmail (Twitter)
