This one is not free but we love it so much that we had to share it! Argon Dashboard a premium admin dashboard built with Bootstrap 4 by our friends from Creative Tim. It is features over 200 individual components, giving you the freedom of choosing and combining. All components can take variations in color, multiple states for colors, styles, hover, focus, that you can easily modify using Sass files.
This Dashboard is coming with pre-built examples, so the development process is seamless, switching from our pages to the real website is very easy to be done.
You will also get a 20% discount if you use the following coupon code: FREEHTML5