Onsen UI is a UI framework for developing hybrid and online mobile apps. It includes all of the necessary UI components for a mobile app's user experience. To support ALL frameworks, the CSS Components are written in cssnext, while the Web Components are written in native JavaScript. The Framework Bindings were intended to make it easier to integrate popular frameworks like Vue.js, AngularJS 1, Angular 2+, and React with each other.

Tailwind CSS is a highly flexible, low-level CSS framework based largely on the concept of utility classes, which are also available in Bootstrap out of the box. You can use utility classes to mix and match CSS properties without resorting to inline styles. It comes with a menu of predesigned widgets to help you develop your site, but it doesn't force you to make difficult-to-undo design mistakes.

Created by Yahoo, YUI is a popular frontend framework. The project is accessible on GitHub for free and is open-source. It has features for a variety of circumstances, including DOM manipulation and event handler association, as well as the creation of complex layouts using a grid system, animations, widgets, and skins, among other resources.

HTML5 Boilerplate is a frontend template that uses HTML5, CSS3, and JavaScript. It may be used to create any type of web page and aids in the development of quick, strong, and adaptive web apps or sites. It comes with all the necessary building elements in a vanilla frontend bundle to develop a small or complicated website, such as CSS helper classes, default print styles, and other programming languages such as jQuery, Modernizr, and CSS.

Mueller is based on Compass and Syntactically Awesome Style Sheets (Sass) (open-source CSS Authoring Framework). It's primarily used for prototyping, but it can also handle backgrounds, borders, margins and paddings, radius, and other typographic effects. To construct a responsive design, developers can manually add rows and columns to a grid; Mueller will take care of the rest.

Simple Grid is a 12-column, minimalist CSS grid that will speed up the creation of responsive websites. You can get started by downloading the CSS stylesheet and adding the necessary classes to your markup.

Unlike other frameworks that include a plethora of fancy features, Simple Grid keeps things simple and provides developers with basic tools to avoid over-enhancing the website's design. The UI elements available in Simple Grid are simple and interactive for a smooth web experience.

Metro UI comes with over 100 user interface components to assist you in creating any type of website. It includes a variety of designs, functionalities, and templates. Metro UI also includes a JS library called M4Q, which acts as a replacement for jQuery and is the foundation for numerous JS-based features. It's simple to use and stylish, featuring a variety of standard components such as a button, tile, menu, date picker, and more.

Ink is a front-end framework that uses HTML, CSS, and Javascript to create faster user interfaces. Developers can also use the INK framework to access pre-designed cookbooks, allowing them to adapt and use a theme quickly. Tables, tabs, data picker, modal, sortable list, tree view, gallery, form validator, and other reusable interface elements make it simple for developers to construct modern layouts.

Skeleton merely gives developers the most basic components, such as buttons, lists, tables, and forms, in order to jumpstart their development process. Its source code is only about 200 lines long, making it quite light. This framework does not require any compilation or installation.

UIkit is a front-end framework that is free, lightweight, and adaptable. It was created to create pixel-perfect web layouts for mobile and desktop screens. It comes with a number of UI components and can be wired using HTML markup or JS code. This framework has a built-in icon library and compatible CSS preprocessing with Less or Sass.

Bootflat is a framework that is built on top of the Bootstrap framework. Bootflat allows developers to construct appealing web applications quickly and easily, with less repetition. The framework's components are created with HTML5 and CSS3, and it includes numerous built-in color schemes for easy and elegant customization.

Materialize is a new responsive front-end framework based on Google's Material Design concepts. The Material Design framework includes components and animations that give users greater feedback. The UI components (including JS plugins) are quite similar to Bootstrap's, but they appear and feel lighter, making applications more appealing to look at and use.

Topcoat is an open-source component library built purely on web standards CSS and HTML rather than a framework. Topcoat's library works with any JavaScript framework, including Backbone, Angular, etc. It's nothing more than a jumble of CSS and HTML files. It comes with a big number of pre-designed user interface components that may be used in any web design project.

Cirrus offers Simplified responsive layout breakpoints for mobile, tablet, and desktop. Developers can also utilize Cirrus to jumpstart their next project by integrating it with any existing design. Cirrus offers two current layout options: flexbox and grid, which developers may customize to meet their specific development demands.

MontageJS is a free, open-source front-end framework for building modern single-page apps (SPA). Montage Studio, a complete software development kit for creating or managing modern single-page apps, is provided by this framework, albeit the documentation on how to use it is sparse. Data bindings make managing your application's and UI's state easier.

Pure CSS is a CSS framework that consists of a collection of CSS components. The weight of Pure is its defining feature. It's exceptionally light, as it was designed with mobile devices in mind, where minimal file sizes are critical. The framework is entirely made up of CSS. Pure CSS has a small footprint and is separated into separate, self-contained modules. Each module has a modest file size, which is beneficial to websites that require increased efficiency.

Semantic is a user-friendly inheritance structure and high-level theming variables that provide you with complete design control. The main benefit of Semantic UI is that it allows you to write meaningful, human-readable HTML code rather than using unintuitive, verbose approaches like BEM or SMACSS.

Cardinal is a CSS framework designed to be fast, scalable, and easy to maintain. The framework eliminates any extra code-related UI design, making its structure relatively light. Cardinal allows developers to customize features, making it easier for them to build and develop dynamic user interfaces for their websites.

Foundation is an open-source front-end framework that is extensively documented, reliable, and versatile. It comes with a number of essential tools for quickly constructing responsive, mobile-first web projects. Foundation also offers all of an application's fundamental components, including a responsive grid, buttons, basic typography, and a variety of other user interface elements.

Bootstrap is a simple file structure that anyone with a basic understanding of HTML, CSS, and JS can use. It is simple to create user interfaces, but it also enables speedier web development. Bootstrap is offered in two versions: one that is precompiled and the other that is based on source code. Experienced developers prefer the latter version since it allows them to customize the templates to their specific needs.