Assembler CSS

Just-in-time CSS, unlimited possibilities

Quickly prototype and build astonishing websites and UI components without installing and maintaining complicated software stacks.

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Modern UI framework

Static CSS frameworks are shipped bundled with hundreds of classes you never use, resulting in higher load times. Assembler's critical mission is to improve the performance of your website by generating only the minimum amount of CSS each webpage needs.

Reusability for the win

Stop wasting your time by being redundant and create reusable mixins directly inside your CSS code. Apply them to your UI components and experience a better way of making web pages: no hassle, no preprocessing, no software to install.

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New dog, old tricks

If you ever wrote CSS code, then you are already an expert with Assembler CSS. We didn't reinvent the wheel, we made it better, so you can focus on what you do best: awesome web pages and amazing UI components.

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Explore an amazing new Universe!

Assembler CSS comes bundled with tons of great features that make designing complex web pages a walk in the park.


You don’t have to worry anymore about the size of your CSS files since the framework is only ~8kB in size (gzip), and everything else is generated just-in-time.

Blazing fast

We took advantage of existing modern web technologies and built something that is truly high-performant. You can load thousands of UI components, and your page will still render smoothly.

Easy to learn

We designed Assembler CSS to resemble existing technologies and to help users become pro-efficient in using the framework as quickly as humanly possible.

Flexible and extensible

Focus on the important stuff and create reusable mixins and scopes, complex grid templates, or use Assembler CSS to augment your favorite CSS framework.

We've decided to develop Assembler CSS as a reaction to the current state of the ecosystem, not just as a solution to our company's needs. Designing web pages should be an enjoyable creative process, but the magic is lost when you force designers to use complex software to produce CSS

Avatar image Marius Sarca CEO, Software architect
Get started with Assembler CSS