Vanilla JavaScript Plugin

simplezoom.js  

A tiny mobile-friendly library to preview images without modal window.

Plugin Website  Demo

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Lightense Images  

A cool image zoom library inspired by fat/zoom.js and tholman/intense-images.

PhotoSwipe  

Beautiful and very powerful image gallery plugin. A bit on the larger side concerning code base.

file-upload-with-preview  

A library for showing previews and related information of images selected for upload.