Rechois an app that allows users to record a sound and 'leave it' somewhere for someone else to discover. It is a global site-specific storytelling platform where you can hide a soundbite in a physical location for visitors in the future. The sounds you record become part of that location and the only way to listen to that recording is to be standing on the exact spot where it was recorded. Users can see on the app’s map where recordings are located, and then make their way there and tune in to that specific phantom audio time capsule.

A team of Recho-heads left their mark on Roskilde festival this year, with music, confessions, love-letters, guides and probably a number of less savoury offerings. Now whenever you visit the site, the echoes of this summer’s festival will be there to explore.

The City of Copenhagen are using the tool to create a treasure hunt for the city’s inhabitants as well as producing an audio tour for the 500 visiting politicians at the Green Capital Conference.

Tracesis another app that allows you to place content in real world locations. You can then attribute it to a specific person, as well as set the amount of time it will be available. The idea is to make sharing more personalised, more meaningful and a lot more engaging.