F-Stop Media Gallery - Image and video organizer.
Shotwell - Shotwell is an open source photo organizer designed for the GNOME desktop environment.
Camera Roll - Simple Gallery App for Android, with lovely Material Design.
XnView MP - XnView is a free software that allows you to view, resize and edit your images. It supports more than 500 different formats!
Google Photos - All your photos are backed up safely, organized and labeled automatically, so you can find them fast, and share them how you like.
digiKam - Professional Photo Management with the Power of Open Source