All these Bootstrap themes are customized versions of Bootstrap. They don't add any new components or layouts, they simply customize how Bootstrap looks. Use these to give your project a different feel. These are all free and open source, licensed under MIT.
Simply use the delivered CSS files instead of the Bootstrap's original CSS file. The CSS files are custom Bootstrap builds with modified variables. They contain exactly the same components and support the same functionality.
Showing all Bootstrap themes sorted bydownloads