What is miniPaint?
[miniPaint is an] online image editor lets you create, edit images using HTML5 technologies. No need to buy, download, install or have obsolete flash. No ads. Key features: layers, filters, HTML5, open source, Photoshop alternative.
miniPaint operates directly in the browser. You can create images, paste from the clipboard (ctrl+v) or upload from the computer (using menu or drag & drop). Nothing will be sent to any server. Everything stays in your browser. -https://github.com/viliusle/miniPaint
Installing NodeJS
Running miniPaint
Source: https://github.com/viliusle/miniPaint/wiki/Build-instructions