Bootswatch is a collection of free themes for Bootstrap. Check it out at bootswatch.com.
Usage Customization To modify a theme or create your own, follow the steps below in your terminal. You'll need to have Git and Node installed.
Download the repository. Install dependencies: npm install
Make sure that you have grunt available in the command line. You can install grunt-cli as described on the Grunt Getting Started page.
Modify variables.less and bootswatch.less in one of the theme directories, or create your own in /custom.
Type grunt swatch:[theme] to build the CSS for a theme, e.g., grunt swatch:amelia for Amelia. Or type grunt swatch to build them all at once.
You can run grunt to start a server, watch for any changes to the LESS files, and automatically build a theme and reload it on change. Run grunt server for just the server, and grunt watch for just the watcher.