An electronic device of a first user is configured to: connect with a second electronic device of a second user of the plurality of electronic devices over a first peer-to-peer wireless network link when the second electronic device is within a communicable range of the first electronic device; receive from the second electronic device, a second unique code generated by the second electronic device, the second unique code including a second unique identifier of the second electronic device; store on the first electronic device: the second unique identifier; information associated with the proximity of the second electronic device; and information associated with the time when the second electronic device is within the communicable range of the first electronic device; and display a notification on the first electronic device when the second unique identifier is downloaded from a web server to the first electronic device.