nomacs is a free image viewer that is small, fast and able to handle the most common image formats including psd and RAW images.A thumbnail preview of the current folder is included as well as a file explorer panel which allows switching between folders. Additionally, it is possible to synchronize multiple viewers. A synchronization of viewers running on the same computer or via LAN is possible. It allows comparing images and spot the differences (e.g. schemes of architects to show the progress).