Swarm by Foursquare is a mobile app that allows users to share their locations with their friends and create a record of their experiences in a personal lifelog. Swarm launched for iOS and Android devices on May 15, 2014. A spin-off from and former companion app to Foursquare City Guide, Swarm allows users to check-in to a given location, and see who is nearby. These check-ins are chronologically listed to create a personal lifelog for each user, which serves as a digital library for all the places they have been, in a searchable database that can be revisited and shared.