Best tools for Frontend Prototyping

Python web framework with HTMX, no JavaScript needed

FastHTML is an open-source Python web framework by Answer.AI that renders HTML directly from Python functions using HTMX. It eliminates the JavaScript build step entirely, letting developers create interactive web apps with pure Python. FastHTML is designed for AI demo apps, admin tools, and internal tooling where full-stack simplicity matters more than SPA complexity. Built by Jeremy Howard's team.

Ultra-fast desktop apps with TypeScript, Bun, and Zig

Electrobun is an open-source cross-platform desktop app framework that combines TypeScript with Bun runtime and Zig for native performance. It produces 12MB base installs versus hundreds of MB for Electron, while maintaining full web technology compatibility. Electrobun uses the system's native webview instead of bundling Chromium, delivers sub-second cold starts, and provides native OS integrations through a Zig bridge layer.

StackBlitz's browser-based Node.js runtime for instant dev environments

WebContainers by StackBlitz runs Node.js natively in the browser using WebAssembly, enabling full development environments without server infrastructure. It powers StackBlitz and Bolt with instant project startup, npm package installation, and dev server execution entirely client-side. Supports Node.js APIs, filesystem operations, and terminal emulation within browser security constraints.

Builder.io visual canvas with Figma-to-code and code-to-Figma sync

Fusion by Builder.io is a visual development canvas that provides bidirectional sync between Figma designs and production code. Designers edit in Figma while developers work in code, and changes propagate in both directions. Supports React, Vue, Svelte, Angular, and Qwik output with a visual editor for non-developers to make content and layout changes without touching code.

Google Chrome Labs visual design tool for editing live web pages

VisBug is a Chrome Labs browser extension that lets developers and designers edit live web pages visually. It provides tools for moving, resizing, and styling elements directly on the page with point-and-click interaction. Features include margin and padding visualization, typography editing, color modification, and accessibility inspection without touching code or opening DevTools.

All-in-one browser DevTools extension for web developers

Hoverify is a browser extension that consolidates essential web development tools into a single overlay interface. It provides element inspection with CSS details, responsive design testing, accessibility checking, color picking, screenshot capture, and asset downloading. Activated by hovering over any webpage element, it provides instant development context without opening browser DevTools.

Production-ready React animation library, evolved from Framer Motion

Motion (formerly Framer Motion) is the most popular React animation library, providing a declarative API for complex animations, gestures, layout transitions, and scroll-triggered effects. Supports spring physics, keyframes, shared layout animations, and exit animations. Powers animations across thousands of production React applications with an API designed for developer ergonomics.

Animated number transition component for React and frameworks

NumberFlow is a lightweight component that animates number transitions with smooth morphing effects. Numbers roll, slide, and transform between values rather than snapping instantly, adding polish to dashboards, pricing displays, counters, and financial interfaces. Available for React, Vue, Svelte, and vanilla JS with over 6,300 GitHub stars and minimal bundle impact.

Copy-paste React component collection built on Tailwind v4

Origin UI is a curated collection of copy-paste React components built with Tailwind CSS v4 and Radix UI primitives. It provides production-ready UI patterns for dashboards, forms, navigation, data tables, and settings panels. Components are designed to be dropped directly into projects with minimal modification, following modern design conventions with dark mode support.

Collection of 150+ animated React components for landing pages

Magic UI provides over 150 animated React components designed for creating visually impressive landing pages and marketing sites. Components include animated text effects, particle backgrounds, scroll-triggered animations, 3D cards, and interactive elements built on Tailwind CSS and Framer Motion. Copy-paste installation model following the shadcn/ui pattern.

Zero-runtime CSS-in-JS framework with type-safe style authoring

Panda CSS is a zero-runtime CSS-in-JS framework that generates atomic CSS at build time from type-safe style definitions. It provides the developer experience of CSS-in-JS with runtime performance of static CSS extraction. Supports design tokens, responsive styles, conditional variants, and recipes for component style APIs. Over 500k weekly npm downloads with RSC compatibility.

Headless UI component library for React, Vue, Solid, and Svelte

Ark UI is a headless component library providing unstyled, accessible UI primitives for React, Vue, Solid, and Svelte. Built by the Chakra UI team using state machines for predictable behavior across frameworks. Includes complex components like date pickers, color pickers, comboboxes, and tree views that are notoriously difficult to build from scratch while maintaining accessibility.

Codeless browser testing with visual test recorder and scheduling

Ghost Inspector provides codeless browser testing through a visual recorder that captures user interactions and converts them into automated test suites. Tests run on managed infrastructure with scheduled execution, CI/CD integration, and Slack notifications. Features visual comparison for UI regression detection, API testing, and test organization with folders and tags for managing large test suites.

Drag-and-drop authentication flows with visual workflow builder

Descope is an authentication platform featuring a visual drag-and-drop flow builder for designing login and signup experiences. It supports passwordless authentication, social login, MFA, SAML SSO, and passkeys. Raised $53M Series A to build no-code identity workflows. SDKs for web, mobile, and backend with pre-built UI components that reduce auth implementation to minutes.

Google's AI-powered cloud IDE for full-stack app development

Firebase Studio is Google's cloud-based development environment that integrates Gemini AI for building, testing, and deploying full-stack applications. It provides browser-based coding with AI assistance for code generation, debugging, and database design. Connects natively with Firebase services including Firestore, Authentication, Cloud Functions, and Hosting for seamless deployment.

Build and share ML web apps in Python with a few lines of code

Gradio is an open-source Python library for creating interactive web interfaces for machine learning models. It supports any data type including images, audio, video, 3D objects, and dataframes. Apps deploy for free on Hugging Face Spaces with auto-scaling, or can be shared via temporary public links. Gradio 5 adds server-side rendering, WebRTC streaming, and an AI Playground for generating apps.

Browser-native frontend coding agent for production codebases

Stagewise is an open-source frontend coding agent with 6,500+ GitHub stars that runs directly in the browser on localhost. YC S25 backed, it lets developers and designers point-and-prompt on live web applications with full devtools and console access, bridging the gap between visual editing and production codebase modification.

Local open-source AI app builder running entirely on your machine

Dyad is a local-first, open-source AI app builder with 20,000+ GitHub stars that provides a Lovable and Bolt.new alternative running entirely on your machine. It supports React and Next.js frameworks, integrates with Ollama for fully offline AI generation, and works cross-platform on macOS, Windows, and Linux with both cloud and local LLM providers.

Instant serverless TypeScript platform for APIs, crons, and bots

Val Town is a collaborative platform for writing and deploying serverless TypeScript functions instantly from the browser. Create APIs, cron jobs, email handlers, and bots with a single Cmd+S. Features version control, collaboration, and a social coding model where functions can import from other users. YC-backed with 450K+ monthly active users.

React components for building AI chat interfaces

assistant-ui is a TypeScript/React component library for building AI chat interfaces with streaming responses, tool rendering, branching conversations, and LLM provider integrations. It supports Vercel AI SDK, LangGraph, and custom backends out of the box. Used by LangChain, Browser Use, and Stack AI. YC W25-backed with 9,000+ GitHub stars and 450K+ monthly npm downloads.

MCP server for AI-powered UI component generation

Magic MCP is an MCP server from 21st.dev that enables AI agents to generate polished UI components inspired by modern design engineering patterns. It gives coding agents access to a library of high-quality component templates and design patterns, accelerating frontend development through intelligent component scaffolding.

Automate local Chrome browser via MCP

BrowserMCP is an MCP server that enables AI agents to automate a local Chrome browser — navigating pages, clicking elements, filling forms, extracting content, and taking screenshots. It gives coding agents the ability to interact with web applications the way a human would, directly from Claude Desktop, Cursor, or any MCP client.

Visual regression testing for CI/CD pipelines

Argos CI is a visual regression testing platform that automatically catches unintended UI changes in CI/CD pipelines. It integrates with Playwright, Cypress, Storybook, and Puppeteer, featuring a stabilization engine that filters flaky pixel differences from genuine regressions. Used by teams at Meta and MUI for frontend quality gates.

AI design tool that edits React in your codebase

Tempo Labs is a YC-backed AI design and prototyping tool that generates and edits React code directly within a developer's existing codebase, maintaining project styles and conventions. Unlike tools that produce standalone code, Tempo supports both greenfield and brownfield projects, understanding existing component libraries, theme systems, and coding patterns to generate code that fits naturally.