jQuery Lightbox - jQuery Lightbox plugins are utilized to showcase images and other web stuff using modal dialogs.
LightGallery - A modern, electron and nodejs based image viewer for Mac, Windows and Linux.
Fancybox - fancyapps.com - Fancy App Store
PhotoSwipe - JavaScript gallery, no dependencies.
Magnific Popup - The greater part of Lightbox modules will completely preload a picture before showing it.
StreamDocs Online - Embed PDFs into your web apps with a few lines of code.