Abstract: Described are methods and apparatuses, including computer program products, for mobile proximity-based notifications. The method includes receiving, by a mobile first device in proximity with a second device, an identifier wirelessly transmitted by the second device. The identifier is associated with a user of the second device. The method also includes determining, using an application running on the mobile first device, whether the identifier is included on a preexisting list stored on the mobile first device. The method also includes notifying a user of the mobile first device, if the identifier is included on the preexisting list, that the user associated with the identifier is in proximity to the mobile first device.