As long as there are algorithms impacting revenues there will be people trying to game them. In the world of mobile apps there are two sorts of algorithm that can be routes to success, chart rankings and search rankings. Chart rankings are very simple and typically just use some time-weighted download volume. Search rankings are much more complex, involving keywords, reviews and other social or similarity-based data as well as downloads. Developers can use a range of tactics to improve their ranking in these algorithms, some of them much more legitimate than others.

There’s no such thing as a bad download

Whilst there are very good practices for optimising search ranking, such as using tools that monitor competitors and analyse their keyword usage to suggest improvements to your own, the single most effective way to improve all rankings is to increase downloads. For paid apps, all downloads generate revenue, whether the app gets used or not – temporarily reducing the price or making the app free is an effective technique for boosting downloads, which boosts rankings and subsequent revenue when the price is returned to normal. For apps that are free anyway, it can similarly be worth spending some of the revenue earned through advertising or in-app purchases to increase downloads. On one level this is obvious, it’s worth spending money to market the app and try to reach new users. However, the winner takes all nature of app store discovery at present makes it worthwhile for some developers to chase downloads purely to enhance their rankings. Even users who will never open the app are worth attracting if they can be acquired for a low enough cost.

Paid placement

There are lots of advertising options available that drive users to your app in the store. The vast majority of them are pay-per-click and thus cannot be used cost effectively to inflate downloads of an app that doesn’t generate significant revenue per user anyway. Most of these are clearly advertising products, others look like app discovery tools to end users. Hooked is a good example of an app that blurs the line between discovery and advertising. They have a popular social discovery app for Android games where developers can pay to generate installs. For developers this is a very logical option because they have a fixed cost for installs which they can compare against average revenue per user. On the other hand, users may believe they’re getting a recommendation when in reality they are seeing an advert. It’s the same argument that surrounded paid placement for search results in the days before Google launched AdWords.

Cross Promotion

Another way to reach users is through similar apps. Apps promoting one another is a great way to reach a common user base. There are several cross-promotion networks with a variety of business models. Ironically the one with the name most suggestive of ranking manipulation, Chartboost, is at the most ethical end; they provide completely free technology for developers to organize their own cross-promotions and also a marketplace to connect developers where they take a cut of the transactions. At the same time, the most popular cross-promotion network (according to our latest survey), Tapjoy, plays much closer to the lines of acceptable conduct. One (and in fairness it should be emphasised only one of several) of Tapjoy’s services is incentivised downloads, a practice that Apple have repeatedly cracked down on – they pay users (in virtual rewards such as in-game currency) to download apps which have paid for that service (in cash). Clearly a large fraction of people who will download other apps to earn a bit of virtual currency are those unable or unwilling to pay for the same. These users almost by definition are unlikely to monetize, so the only obvious reason to seek them out is to increase rankings in order to be discovered by other paying users that would be more expensive to reach directly.

Shuabang!

At the extreme end of ranking manipulation, with no pretence of being anything else, is Shaubang. This manipulation is primarily practiced on Apple’s App Store, made possible by the fact that a credit card is not required for an iTunes account in China. Companies with millions of accounts make use of extremely cheap local labour to pay people to download and review apps. These services often guarantee to boost an app to a desired category ranking for a fixed fee. This practice is heavily frowned upon by store owners but also extremely hard to police, since it involves real users (sometimes bot-assisted for efficiency) with real accounts.

Where’s the harm?

Users are mostly getting what they want out of these deals and so are the developers involved. Store owners have higher download stats to boast about. Even at the extreme end we have job creation in China. The main people losing out are the developers not taking advantage of these strategies. However, if ranking manipulation becomes the norm rather than a fringe behaviour then two problems become very serious. First, the top ranked apps are simply the ones that paid the most to be there, rather than the best ones – this makes discovery of genuinely great apps harder and reduces the overall perception of app quality. Second, a feedback cycle further concentrates revenue at the top of rankings – only those who pay to be at the top can afford sufficient manipulation to stay there and the rankings will begin to stagnate. App store owners need to ensure their markets are as honest and fair as possible, or users and honest developers will suffer in the long run.