digiKam - Professional Photo Management with the Power of Open Source
F-Stop Media Gallery - Image and video organizer.
Photos on macOS - Photos keeps your images organized and accessible. Rediscover favorite shots with Memories. Access them on your devices with iCloud Photos.
A Photo Manager - Manage local photos on Android: gallery, geotag with photomap, tags, find, sort, view, copy...
XnView MP - XnView is a free software that allows you to view, resize and edit your images. It supports more than 500 different formats!
LeafPic - LeafPic is a fluid, material-designed alternative gallery.