Preline UI is an open-source set of prebuilt UI components based on the utility-first Tailwind CSS framework.

Source code: https://github.com/htmlstreamofficial/preline

From the https://design.wonderflow.ai/, here are the Stories of each component.

Reasonable Colors is an open-source color system for building accessible, nice-looking color palettes.

Manual-writing styled forms with a CSS only file.

The font Short Stack should also be used. It is available as NPM package.

A react-style library (but only 4 kB!). It is so small and uses JSX.

A component created with Atomico can be used in Html, Vue, Preact, React, Svelte, Solid or any other library.

This seems relevant for small projects or one that needs little interaction without using bare JS. The Lit library needs for example a lot of boilerplates. Here we need a function.

It uses WebGL for it.

Unstyled, accessible components for building high‑quality design systems and web apps in React.

We need this in other frameworks!

Using finite-state machines seems to be a good idea!

A collection of framework-agnostic UI components patterns like an accordion, menu, and dialog that can be used to build design systems for React, Vue, and Solid.js

A collection of UI components made with HTML and CSS

It is possible to display high, medium and low screen sizes by popularity

Another collection of CSS loaders and spinners

Another list of CSS spinners

Customizable CSS loaders and spinners

Another background css pattern generator

Another one: https://patternizer.com/4rvv

Useful for flat design