nomacs is a free, open source image viewer, which supports multiple platforms. You can use it for viewing all common image formats including RAW and psd images.
nomacs vs Microsoft Photos opinions
I just want a photo viewer that is simple and fast without extra luggage, nomacs is just that
XnViewMP is a free software to view, organise, convert graphics and photos files or to create slide show, contact sheet, HTML pages.
qView is a Qt-based image viewer designed to be practical and minimal, available for Windows, macOS, and Linux
qView vs Microsoft Photos opinions
It's a lightweight alternative to Microsoft's Photos app. For LTSC users like myself, it is useful to have a modern photo viewer, allowing us to skip Windows Photo Viewer. Highly recommend!
it is more simplistic, faster in loading images and doesn't come with stuff like video editor like windows photos does. it is also open source and therefore it's perfect.
ACDSee is a complex, multi-purpose application that serves for viewing, organizing and editing digital photos. Furthermore, images can be shared on social websites or your own space on the developer’s website.
Photos is a digital photograph manipulation application developed by Apple, intended to be less complex than its predecessor iPhoto .
Bridge CC gives you centralized access to all the files and assets you need for your creative projects. Organize personal and team assets, batch edit with ease, add watermarks, set centralized color preferences, and even upload your photos to Adobe Stock.
Tonfotos simplifies browsing of large photo collection by grouping shots by events, dates, people, locations and so on. Quickly find what you need regardless where files are stored - on your computer, external drives or NAS.
Xee is an streamlined and convenient image viewer and browser. It is similar to macOS's Preview.app, but lets you easily browse the entire contents of folders and archives, move and copy image files quickly, and supports many more image formats.