The project's README from github.com/thesysdev/openui. As one markdown file: README.md.
OpenUI is a full-stack, framework-agnostic Generative UI framework built around a compact, streaming-first language. A framework-agnostic core powers first-party runtimes for React, Vue, Svelte, and Angular, and React additionally ships built-in component libraries and ready-to-use chat interfaces. OpenUI Lang uses up to 67% fewer tokens than JSON.
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Important: OpenUI has no official cryptocurrency, token, or coin. Any asset using the OpenUI name is unaffiliated with this project and is not endorsed by its maintainers.
At the center of OpenUI is OpenUI Lang: a compact, streaming-first language for model-generated UI. Instead of treating model output as only text, OpenUI lets you define components, generate prompt instructions from that component library, and render structured UI as the model streams.
Core capabilities:
npx @openuidev/cli@latest create --name genui-chat-app
cd genui-chat-app
echo "OPENAI_API_KEY=sk-your-key-here" > .env
npm run dev
This is the fastest way to start with OpenUI. The scaffolded app gives you an end-to-end starting point with streaming, built-in UI, and OpenUI Lang support.
What this gives you:
Your components define what the model can generate.
flowchart LR
A["Component Library"] --> B["System Prompt"]
B --> C["LLM"]
C --> D["OpenUI Lang Stream"]
D --> E["Renderer"]
E --> F["Live UI"]
Try it yourself in the Playground: generate UI live with the default component library.
| Package | Best for | Description |
|---|---|---|
@openuidev/lang-core |
Framework-agnostic parsing and prompt generation | Core parser, prompt-generation, runtime-evaluation, and type layer with no React, Angular, Vue, or Svelte dependency |
@openuidev/langchain |
LangChain and LangGraph agents | Agent transformer and server helpers that stream OpenUI through AG-UI |
@openuidev/react-lang |
React rendering runtimes | Define component libraries, generate prompts, and render streamed OpenUI Lang in React |
@openuidev/react-headless |
Bring-your-own React chat UI | Headless chat state, streaming adapters, and message format converters |
@openuidev/react-ui |
Fastest path to a full React chat experience | Prebuilt chat layouts, standalone UI primitives, and two built-in component libraries |
@openuidev/react-email |
Email generation and HTML export | React Email component definitions plus prompt options for model-generated emails |
@openuidev/assistant-ui |
assistant-ui apps | Tool UI renderers and instruction wiring for streaming OpenUI Lang inside assistant-ui |
@openuidev/vue-lang |
Vue integrations | Vue 3 bindings for defining model-renderable components and rendering streamed OpenUI Lang |
@openuidev/svelte-lang |
Svelte integrations | Svelte 5 bindings for defining model-renderable components and rendering streamed OpenUI Lang |
@openuidev/angular-lang |
Angular integrations | Angular bindings for defining component libraries and rendering streamed OpenUI Lang |
@openuidev/browser-bundle |
CDN, iframe, and no-build embeds | Prebuilt browser bundle that ships the renderer, UI library, React, and styles as script + stylesheet assets |
@openuidev/a2ui |
A2UI with OpenUI Lang component payloads | Framework-agnostic A2UI v1.0 protocol client with an optional React renderer |
@openuidev/server |
Server side utilities | Server utilities for OpenUI and OpenUI Gateway |
@openuidev/observability-cloud |
Hosted observability in the Thesys console | Cloud sink that batches OpenUI events and ships them to OpenUI Gateway |
@openuidev/cli |
Project scaffolding and prompt generation | CLI for creating new apps and generating system prompts or JSON schema from a library definition |
@openuidev/openclaw-os-plugin |
OpenClaw workspaces | OpenClaw OS plugin for serving OpenUI-powered OpenClaw workspaces |
Common starting points:
# React app with OpenUI rendering and prebuilt components
npm install @openuidev/react-lang @openuidev/react-ui
# Framework-agnostic backend or Edge prompt generation
npm install @openuidev/lang-core
# LangChain/LangGraph agent and server integration
npm install @openuidev/langchain @langchain/langgraph
# Vue, Svelte, or Angular runtime
npm install @openuidev/vue-lang
npm install @openuidev/svelte-lang
npm install @openuidev/angular-lang
# A2UI protocol with OpenUI Lang component payloads
npm install @openuidev/a2ui zod
OpenUI Lang is designed for model-generated UI that needs to be both structured and streamable.
Measured with tiktoken (GPT-5 encoder). OpenUI Lang vs two JSON-based streaming formats across seven UI scenarios:
| Scenario | Vercel JSON-Render | Thesys C1 JSON | OpenUI Lang | vs Vercel | vs C1 |
|---|---|---|---|---|---|
| simple-table | 340 | 357 | 148 | -56.5% | -58.5% |
| chart-with-data | 520 | 516 | 231 | -55.6% | -55.2% |
| contact-form | 893 | 849 | 294 | -67.1% | -65.4% |
| dashboard | 2247 | 2261 | 1226 | -45.4% | -45.8% |
| pricing-page | 2487 | 2379 | 1195 | -52.0% | -49.8% |
| settings-panel | 1244 | 1205 | 540 | -56.6% | -55.2% |
| e-commerce-product | 2449 | 2381 | 1166 | -52.4% | -51.0% |
| TOTAL | 10180 | 9948 | 4800 | -52.8% | -51.7% |
Full methodology and reproduction steps in benchmarks/.
Detailed documentation is available at openui.com.
openui/
├── packages/
│ ├── react-lang/ # Core runtime (parser, renderer, prompt generation)
│ ├── react-headless/ # Headless chat state & streaming adapters
│ ├── react-ui/ # Prebuilt chat layouts & component libraries
│ ├── react-email/ # React Email component library for generated emails
│ ├── assistant-ui/ # assistant-ui Tool UI renderers for OpenUI Lang
│ ├── lang-core/ # Framework-agnostic parser, prompt, and runtime layer
│ ├── langchain/ # LangChain/LangGraph streaming integration
│ ├── vue-lang/ # Vue runtime bindings for OpenUI Lang
│ ├── svelte-lang/ # Svelte runtime bindings for OpenUI Lang
│ ├── angular-lang/ # Angular runtime bindings for OpenUI Lang
│ ├── browser-bundle/ # Script-tag bundle for CDN / iframe / no-build embeds
│ ├── a2ui/ # A2UI protocol with OpenUI Lang component payloads
│ ├── server/ # Server utilities for OpenUI & OpenUI Gateway
│ ├── observability/ # Framework-free observability event bus
│ ├── observability-cloud/ # Cloud sink shipping OpenUI events to Thesys
│ ├── devtools/ # Dev-only OpenUI Inspect widget
│ └── openui-cli/ # CLI for scaffolding & prompt generation
├── examples/ # Cookbooks and integration reference implementations
│ ├── agent-frameworks/
│ ├── app-frameworks/
│ ├── cookbooks/
│ ├── design-systems/
│ ├── harnesses/
│ └── miscellaneous/
├── docs/ # Documentation site (openui.com)
└── benchmarks/ # Token efficiency benchmarks
Good places to start:
examples/README.md to find a focused reference implementationCONTRIBUTING.md if you want to contribute| Feature | OpenUI | json-render (Vercel) | A2UI (Google) | CopilotKit OpenGenUI |
|---|---|---|---|---|
| Tokens | 1x | 3x | 3x | 4x |
| Latency (60 tok/s) | 4.9s | 14.2s | 14.2s | ~20s |
| Streaming | Yes | Yes | Yes | Partial |
| Consistent output | Yes | Yes | Yes | No |
| Components | Library + custom | Library + custom | Custom only | None |
| Multi-platform | Web, mobile, email | Web, mobile, PDF, email, video | Web, iOS, Android | Web |
| Built-in data fetching | Yes | No | No | No |
| Chat UI included | Yes | No | No | Yes |
For more details, refer to the official OpenUI Lang comparison documentation.
A list of organizations and projects using OpenUI is maintained in ADOPTERS.md. If you're using OpenUI, please consider adding your organization; it helps the project gain momentum and helps other adopters find peers using OpenUI in similar contexts.
Contributions are welcome. See CONTRIBUTING.md for contribution guidelines and ways to get involved.
OpenUI ships an Agent Skill so AI coding assistants (Claude Code, Codex, Cursor, Copilot, etc.) can help you scaffold, build, and debug Generative UI apps using OpenUI Lang.
The skill is maintained in the thesysdev/skills repository.
# With the skills CLI (works across all agents)
npx skills add thesysdev/skills --skill openui
The skill covers component library design, OpenUI Lang syntax, system prompt generation, the Renderer, SDK packages, and debugging malformed LLM output.
Found a bug or have an idea? Open an issue, or send anonymous feedback from your terminal:
npx @openuidev/cli feedback "Describe the problem or idea"
Coding agents using the OpenUI skill can send feedback for you. They remove personal details and code from the message and ask for your approval before sending it.
This project is available under the terms described in LICENSE.