A notification system notifies users when there is a match between images. The notification system includes a network interface receiving images from a plurality of user devices including a first user device and a second user device, a memory storing database and instructions, and a processor. The processor executes the instructions to function as an image processing unit processing the received images, a face recognition unit recognizing one or more faces in each received image, a face matching unit checking whether a face in a first image from the first user device matches a face in a second image from the second user device, a metadata processing unit processing metadata in each received image, and a notification unit notifying the first user device and the second user device in a case where the face in the first image matches the face in the second image.