UI Design GitHub Repositories (2026) · Open Source Tools

Agent skills that give coding agents taste: art direction, reference images and a browser check instead of generic AI pages

An AI skill that provides design intelligence for building professional UI/UX across multiple platforms.

🌼 🌼 🌼 🌼 🌼  The most popular, free and open-source Tailwind CSS component library

Rules for an AI coding agent to filter out generic AI-generated UI designs, text, and code.

ReaLTaiizor is a .NET WinForms control library that offers a wide range of components and is user-friendly and design-focused.

Codex plugin for OpenPencil — an interactive Rust/WASM canvas for AI-assisted UI design. Create editable .op files from prompts, refine selected elements, generate image assets, and install with one prompt on macOS, Windows, and Linux.

Website for Meshery

200 web animation examples with copy-ready AI prompts + MotionLens: turn any site's animation into a prompt. React, TypeScript, Framer Motion, Three.js

Open-source design-method engine for Claude Code, Codex & Cursor. 23 agent skills for fixed design judgment, multiple grammars, semantic palettes, reference compilation, and evidence-verified UI. MIT.

The Pencil Project's unique mission is to build a free and opensource tool for making diagrams and GUI prototyping that everyone can use.

A soulful, production-grade PDF reader for Android featuring a "Warm Paper" aesthetic, gesture-driven interface, and a high-performance modular architecture. Built with Kotlin 2.0 and Jetpack Compose

React UI components of the Yamada, by the Yamada, for the Yamada built with React and Emotion.

Design system library by pixiv

Layer5 Design System

A multifunctional notepad-based caclulator

A free, open-source add-on for Claude, ChatGPT, Codex and Cursor that turns a few plain answers into a design system, so everything you build looks like it belongs together.

BezelKit is a Swift package designed to simplify the process of accessing device-specific bezel sizes in apps. Knowing the exact bezel size can be crucial for aligning UI elements, creating immersive experiences, or when you need pixel-perfect design layouts.

Eighteen warm, light color themes for Hermes Desktop, with readable UI refinements and a simple installable plugin.

MCP server and design skill that grounds coding-agent UI work in real product screens. Two tools, npx-installable.