Bootstrap

Bootstrap is an open source front-end toolkit for building responsive websites. It bundles a grid system, ready-made components and JavaScript plugins, so you can start a layout quickly.

You add the framework to a page and use its classes for layout, spacing, buttons, forms, navigation and other common parts. The styles are written in Sass, which lets you change colors and variables before compiling. The project also provides an icon set and starter templates for common setups.

• Responsive grid system for page layouts
• Prebuilt components for navigation, forms and more
• JavaScript plugins for common interactive widgets
• Sass variables for colors and theme changes
• Official icon set for interface symbols

Developers and designers who need a dependable starting point for websites or internal tools, especially teams that already know the framework. It is also a common choice for quick prototypes that need to look finished.

Bootstrap is free and open source. The code is licensed under MIT, and the documentation is under CC BY 3.0. The newest major version shown on the site is still an alpha release, so check the release notes before using it in production.