IrfanView - IrfanView ... one of the most popular viewers worldwide.
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
Universal Viewer - Universal Viewer is an advanced file viewer for wide range of formats. Supported file formats are:
digiKam - Professional Photo Management with the Power of Open Source
DBGallery - DBGallery is a digital asset management cloud service (SaaS) and on-prem web-server software package for a range of team sizes.
ImageGlass - You can use Image to view your digital images and photos of many different formats.