photos2webgallery is described as 'Create lovely photo web galleries directly from your Photos library on Mac. Share the generated HTML output folder with your family and friends in any possible way – e.g., via your personal website or external storage'. There are more than 100 alternatives to photos2webgallery for a variety of platforms, including Windows, Mac, Linux, Xfce and PortableApps.com. The best alternative is IrfanView. It's not free, so if you're looking for a free alternative, you could try nomacs or ImageGlass. Other great apps like photos2webgallery are XnView MP (Free Personal), FastStone Image Viewer (Free Personal), XnView (Free Personal) and JPEGView (Free, Open Source).
nomacs is a small, fast image viewer able to handle the most common image formats including RAW images. Additionally it is possible to synchronize multiple viewers. A synchronization of viewers running on the same computer or via LAN is possible.
ImageGlass is a simple picture viewer with which you will be able to display your image collection in a very similar way to the one that Windows provides by default, but with some additional functions.
FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor. It has a nice array of features that include image viewing, management, comparison, red-eye removal, emailing, resizing, cropping and color adjustments.
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.