If you search in Yandex or Google, you're guaranteed to find a huge—no, an incredible—number of tools designed to improve your website's performance. Of course, much depends on image optimization and working with a CDN. But there's one thing web developers often focus on the most: code optimization.
Code optimization can mean reducing the number of HTTP requests, minimizing file sizes, and using custom frameworks already optimized for speed. Bootstrap v4, for example, is a powerful and versatile tool, but it's quite heavy. But we’re not here to talk about that.
Previously, we’ve reviewed different frameworks for different tasks, but most of them were rather “big.” And as we know, the bigger the application, the larger the project usually becomes. In this article, we’ll look at some of the smallest frameworks you can use to potentially replace Bootstrap. Of course, not all its functionality can be transferred, but you can still apply specific features. And yes, you might be amazed at just how powerful these tiny tools are. And no, it’s not fiction! Especially considering that most of them are modular—meaning you can disable, skip, or omit parts you don't need… and that reduces your code size overall.
Small but mighty
Topcoat
Using Topcoat, developers get an excellent framework optimized for speed. The developers specifically tested individual modules for performance and execution time. At the same time, the framework is easy to configure and fits any type of website.
And that’s not even mentioning that the framework is mobile-optimized, uses CSS BEM naming, allows for custom styles, supports PSD files, and much more.
Pure CSS
Created by Yahoo, this framework is incredibly responsive and loads almost instantly. The best way to describe it is a collection of tiny, responsive CSS modules for any website. Like Milligram (see below), Pure is based on Normalize.css, features responsive design for elements, but has a small style set—so you can easily customize it to include menus, buttons, forms, and various combinations.
If you only want to use the grid, you can download a separate module (about 0.8 Kb)—much smaller than Bootstrap or Foundation. Plus, it uses a 24-column grid.
Petal
Petal is a fairly lightweight frontend framework for creating custom UI designs. It includes support for some components but is primarily based on LESS CSS and serves as an alternative to Sass libraries.
The framework is still evolving—the current stable version is v0.11.1—and the Shakr development team is heavily investing in its growth, so it’s not going anywhere anytime soon.
All Petal components are optional, so you can slim down your site by removing unused ones. Notably, there’s extensive documentation covering components, grids, buttons, and code snippets.
Mincss
This framework is promoted as a minimized alternative to Bootstrap. In reality, it’s a tiny UI framework that works in all major browsers and supports some legacy ones like IE6+.
It's ideal when your site needs to be as lightweight as possible. Mincss uses fewer extra divs and classes than its competitors, while still producing readable, semantically correct code.
Sure, Mincss has fewer features than Bootstrap, but you can port some Bootstrap code into Min and optimize it with a special plugin. You can even combine Min with Bootstrap to expand functionality.
Milligram
Another tiny frontend framework for UI work. It doesn’t offer many styles but lets you build a clean project. The package weighs just 2Kb but ranks among the top three simplest tools. You can install it using Yarn, Bower, or npm.
What makes this CSS framework unique is that you won’t find components or dynamic features like those in Bootstrap. Milligram focuses on buttons, typography, quotes, and a flexbox-based grid system. It's ideal for developers wanting to build quick layouts without complexity.
Kube
This framework can impress even expert developers with its tiny size—30 Kb, including all JS libraries. For reference, Kube is about 20 times smaller than Bootstrap (which is roughly 600 Kb).
Still, Kube isn’t really competing with something like Mincss because it comes packed with modules and features. But if that’s what you need, it’s a fantastic library!
Kube has extensive documentation and looks very professional—making it suitable for team projects.
Furtive
The self-proclaimed minimalist framework Furtive weighs about 2.4Kb and is one of the few mobile-first structures with a large class and function library.
It also supports the latest browser technologies, is based on Normalize.css, and works with SVG and Flexbox, making it easy to reduce code and improve page load times.
Siimple
This modular, tiny framework is built with SASS/SCSS, inspired by flat design, and features extremely clean code. Siimple brings minimalism to a new level, offering a “clean” approach to both design and code. Everything—colors, typography, grids—is created in a flat style that remains popular and unique. The code is incredibly clean, simple, and readable.
For example, take a look at the documentation and ask yourself: “Is this framework really suitable for rapid prototyping or building a user layout from scratch?”
Picnic
With Picnic.css, web developers get exactly what the creators promise—no more, no less. A lightweight, beautiful interface optimized for project speed. It might remind many of a simplified Bootstrap, but with plenty of room for aesthetic, well-designed projects.
You can use this framework for any type of website—portfolio, online store, business portal, or corporate platform. To see Picnic in action, visit the demo page and check out the full documentation.
Do You Even Need a CSS Framework?
Just like we’ve discussed JS libraries and add-ons for popular site-building tools before, here we explored CSS frameworks. But if you're wondering whether you really need one, ask yourself: “What’s more convenient—writing all my own CSS styles, or using tested templates, practices, and toolkits designed for performance and efficiency?”
Using ready-made solutions saves time, prevents code errors, and avoids monotonous work. Whether you’re a pro or a beginner, whether you master HTML, CSS, JS—it all comes down to streamlining your workflow.
Each framework has its strengths, weaknesses, and specific use cases, letting you choose the right one for each project. If your project is simple, no need to use something overly complex. Plus, many of the frameworks mentioned are modular, so you can pick and mix only what you need. That’s why many developers work across multiple frameworks—borrowing a style here, a grid system there, and a component elsewhere. Vive la modularité! :)
Lastly, with Flexbox and Grid Layout now widely supported in modern browsers, building complex website layouts has never been easier.
Final Thoughts
Whether you love working with prebuilt solutions or prefer writing every style by hand, whether you maintain your own personal codebase or just reuse chunks from project to project—frameworks will be useful sooner or later. Whether you're a beginner or a pro, they can either do the work for you or provide clean, well-structured code that enhances and speeds up your website.
Of course, there are tons of CSS frameworks out there—this is just a selection of the smallest ones. Maybe you’ll find one here that’s perfect for your next project—or maybe you’re already using one of them.