Facebook has added extra functionality to app download campaigns being deployed on its platform to help app owners drive engagement and conversions.

Using ad IDs, email addresses or phone numbers of current app users, marketers can now retarget people with direct links back into an app, encouraging them to do things like shop, book, listen or play. Users can be directed to brand new content, like sales or new levels on a game.

Facebook says brands like eBay and HotelTonight, the last-minute booking app, have used Facebook app install campaigns to drive more than 145m downloads on iOS and Android todate. But it has acknowledged that downloads are only part of the job.

Facebook has updated SDKs for iOS or Android to help measure the effectiveness of app install campaigns, with 14 predefined events, including purchased in a retail app or level achieved. Marketers can also create custom events or employ a mobile measurement partner to help measure installs.