Paged.js is a free and open-source library that paginates any HTML content to produce beautiful print-ready PDF. The library fragments the content, reads your CSS print declarations and presents a paginated preview in your browser that you can save as PDF.

DropzoneJS is an open source library that provides drag’n’drop file uploads with image previews.

Media queries are what make modern responsive design possible. With them you can set different styling based on things like a users screen size, device capabilities or user preferences. But how do they work, which ones are there and which ones should you use? Here's the complete guide to media queries.