Guidebook is an app – the app, perhaps – for event organisers. It is billed as an easy, inexpensive way of creating mobile guides for events, no matter how small or large. Built-in Twitter integration allows users to tweet direct from the app, while device-specific design ensures that it is optimised for iOS as well as Android. Metrics tracking gathers data for you. Already tried and tested on 30,000 events around the world, the app has been downloaded more than 7m times. Recent updates include the addition of a one-to-one messaging function. The standard version is free and offers users a chance to try Guidebook’s features before choosing to upgrade.