Power management techniques for crowd-sourced lost-and-found service are described. A mobile device participating in the crowd-sourced lost-and-found service can monitor signals from an electronic tag using a first subsystem that has low power consumption. The mobile device can monitor wireless signals from wireless access points (APs) using a second subsystem that has low power consumption. Identifiers of detected tags and APs are stored locally in the respective subsystems. At pre-specified intervals, the subsystems can submit the stored identifiers to an application processor of the mobile device. The application processor can be activated to determine the location of the tags using known location of the APs. The application processor can be deactivated after the location of the tags are determined. The mobile device can then submit the location to a remote server. The remote server can provide the location to an owner of an item attached to the tag.