The C3 Services team has reviewed and compiled our top 10 list of free and open source frameworks for professional web developers. Our top 10 list makes it easy for any developer to get started creating awesome customized responsive websites and mobile applications.

1. Bootstrap

Bootstrap lets you quickly develop and customize responsive mobile-first sites, with the world’s most popular front-end open source toolkit, featuring Sass variables and mixins, responsive grid system, extensive prebuilt components, and powerful JavaScript plugins.

Getting started with Bootstrap is easy with jsDelivr and template starter pages. For the first time ever, Bootstrap has its own open source SVG icon library, designed to work best with their components and documentation. Bootstrap is free open source licensed under the MIT License.

2. Foundation

Foundation is a Framework for any device and accessibility. Foundation is a family of responsive front-end frameworks that make it easy to develop modern responsive websites, apps and emails that look amazing on any device. Foundation is semantic, readable, flexible, and completely customizable. Foundation is constantly adding new resources and code snippets, including free HTML templates and code to help get you started.

Foundation framework is features-packed to help developers quickly build content-focused websites. Foundation framework provides developers with HTML, CSS, & JavaScript to help you quickly prototype. Foundation is easy to customize & extend to get your project polished & completed. Foundation is free open source licensed under the MIT License.

3. Tailwind CSS

Tailwind CSS lets developers quickly build modern websites without ever leaving your HTML. Tailwind CSS is a utility-first CSS framework packed with classes like flex, pt-4, text-center and rotate-90 that can be composed to build any design, directly in your markup.

Tailwind framework is so low-level, it never encourages you to develop the same website twice. Tailwind CSS makes it easy to build the same component with a completely different look in your next project.

4. Semantic UI

Semantic framework is for developers to help you create beautiful, responsive layouts using human-friendly HTML. Semantic comes equipped with an intuitive inheritance system with high level theming variables that gives developers complete control and design freedom.

Semantic framework lets you develop your UI once, then deploy with the same code everywhere. Semantic is developed completely with em, making responsive sizing fast and easy. Semantic has design variations built into elements, allowing developers to make the choice how content adjusts for mobile devices. Semantic is free open source licensed under the MIT License.

5. Concise CSS

Concise CSS is bloat-free with no unnecessary styles added so you can spend more time building and less time overriding. Comcise CSS is a framework built with design in mind. Allowing developers to get better results from the beginning with less code. Concise has a smaller learning curve; the simplicity of the styles helps developers get started faster.

Concise provides a basic UI kit as an add-on. Concise also provides utility classes for rapid prototyping and context-dependent styles.

6. Milligram

Milligram is a minimalist CSS framework, providing a minimal setup of styles for a quick and clean starting point

Milligram is free open source licensed under the MIT License.

7. Luda

Luda is a library that helps developers to build cross-framework UI components. Luda lets developers build reusable components, then package them in any framework with less effort, no matter in a front-end framework or a back-end framework.

Luda lets developers focus on component functions, under a straight-forward and familiar process like using jQuery, without worrying about lifecycle handling and cache management. Luda is free open source licensed under the MIT License.

8. Mustard UI

Mustard UI is not your average CSS Framework. Mustard UI is a starter CSS framework that actually looks good.

Mustard UI was developed to address the growing concern of CSS frameworks that look pretty awful. We kept what we liked about CSS and adapted it into a lightweight production ready library. Mustard UI is free open source licensed under the MIT License.

9. Cutestrap

Cutestrap is a strong, independent CSS Framework. Only 2.7KB minified & gzipped. Cutestrap is a progressive CSS Framework developed with modern techniques and an eye for the future, combined with a simple API and robust customization options.

Cutestrap is free open source licensed under the MIT License.

10. Alux

ALUX is a Lightweight Framework for developing Blazing-Fast and Beautifully Responsive Web Apps. The Framework is developed with HTML/CSS and pure Javascript. ALUX is Dependencies Free, no jQuery but with a wide range of features: Grids, Sliders, Menus, Animations, Typography, Forms, Buttons & more.

ALUX is free open source licensed under the MIT License.