How big is WhatsApp? They've never said, but there are some indications.
First, the app is at or near the top of the paid downloads and top grossing lists on the Apple app store in pretty much every market: according to AppAnnie, it's currently the no.1 paid app in 121 markets (including all the big ones except for China, South Korea and Japan) and in the 'top 10- grossing' list in 97. The fact that it only costs $0.99 and has no in-app purchases makes the high grossing rank particularly impressive. Meanwhile, it is in the '50-100m downloads' bracket on Google Play, and has been for several months (Facebook is in the '100-500m downloads' bracket).
We know that app download rates on Android and iOS are very roughly similar: iOS is well ahead on paid apps, but Whatsapp, being a money-saver, might be an exception to that and of course it's free for the first year on Android. So, a wild guess based on app store data might be 75m cumulative downloads on Android and 75m on iOS. WhatsApp is also on other platforms - Windows Phone, RIM and Symbian, but I'd be surprised if any of those are significant. The wild card is S40, where WhatsApp has a preload deal with Nokia. I'd expect double-digit millions here (Facebook has over 50m Java users) , but have no solid way to bracket further. Of course, downloads don't necessarily mean users.
Next, this Google Trends chart gives some indication. It compares search volume for Whatsapp (blue), BBM (red) and Viber (yellow). Whatsapp search volume is now much higher than 'BBM', for which RIM reports 60m users, and Viber, an OTT voice and messaging service that reports 90m users.
Adding Skype to the series (in green) is also pretty revealing.
A map view shows some strong geographic concentration, which, for example, bears out anecdote that WhatsApp is very strong in Spain.
It's also interesting to compare this with search volume for 'BBM', which shows exactly the strength in Indonesia that RIM itself reports, together with the strength in the UK that the Blackberry's lingering popularity amongst UK teenaged girls would suggest.
Google Trends, of course, is interesting rather than definitive. This is especially true for smartphone apps, where the main search activity is within app stores rather than on Google. This means that Apple knows more about what's going on here than Google.
The company itself is very deliberately discrete. However, it has given one very telling statistic: on 26 August 2012 it passed 10bn messages a day (4bn inbound, 6bn outbound - the difference being accounted for by group chats).
What might that tell us about active users? An edge-case assumption of 50 messages per user per day would give 80m DAUs. A more reasonable 30 messages/day would give 133m DAUs, and a moderate 'I use this sometimes, and I also use SMS' assumption of 15 messages per day would give 270m DAUs. Naturally, there's a tradeoff: more users with less engagement or fewer users with more engagement.
None of this is especially scientific, but taken together, it seems pretty clear that WhatsApp has well over 100m active users, and possible 2-300m. Skype, incidentally, has 254m MAUs.
In other words, WhatsApp has several times more users than Instagram had when Facebook bought it for what was then $1bn (even now Instagram 'only' has 100m). With a staff of just 35, plus outsourced development in Russia, that's a testament to the scaling possibilities of app stores - and suggests that the M&A industry is pretty much camped out in the WhatsApp offices.
WhatsApp also has revenue, which Instagram famously did not, though how much is even more opaque. It has no advertising and has said it doesn't want it. Rather, revenue, for now, is a one-off fee of $0.99 on iOS and $0.99 a year on other platforms with the first year free. This is pretty unusual. The free entry point on Android makes sense given the poor monetisation rate of that platform, but eschewing recurring revenue on iOS is odd - essentially, WhatsApp will only make money on iOS when it's growing the user base, at least directly.
In addition, though, WhatsApp has started doing carrier bundling deals: a small monthly fee for flat-rate access. Terms are not disclosed but the sticker price is low (just $0.30 per user per month for Reliance in India). I'm not entirely sure how sustainable this is as operators move to bundled tariffs (a subject for a future post), but in any case the revenue per user is also pretty small.
Of course, revenue of a dollar or so per user per year might sound small to a telco, but in the social world it's pretty good: even Facebook only has a run-rate of $5 revenue per user per year.
As should be obvious, WhatsApp is both a headache and an opportunity for mobile operators, which will be the topic of a future post.
UPDATE: Sometime in early November, WhatsApp ticked up from the '50-100m downloads' bracket on Google Play to '100-500m'. Downloads do not, of course, equal active users, but this does point to continuing momentum.