Build MCP apps once, run them anywhere
Build locally with hot reload. Export bundles for ChatGPT, Claude, and any compatible MCP host.
Try the workbench
A local host simulator for ChatGPT- and Claude-style UIs. Preview your app, mock tool calls, and export for production.
Best on desktop
Open this page on a larger screen to run the demo.
Everything you need to ship assistant apps
A local workbench with a production-ready export flow.
See changes instantly. Test desktop, tablet, and mobile viewports with hot reload.
Simulate tool calls with configurable JSON. Cover success, error, and edge cases without a backend.
Optional MCP server template included. Run frontend and tools with a single command.
Export a self-contained HTML bundle with dependencies inlined, ready to deploy.
Preview inline, popup, and fullscreen. See exactly how it looks in ChatGPT or Claude.
Write once, run everywhere. Detects ChatGPT vs MCP and uses the right APIs.
Know what works where
One API surface with platform-specific capabilities for ChatGPT and Claude, ready to feature-gate.
Export and ship
Your production-ready bundle, ready for ChatGPT, Claude, and other MCP hosts.
Deploy export/widget/ to any static host, then update export/manifest.json with the hosted URL. Use that manifest wherever you register the app (ChatGPT or any MCP host like Claude). It’s the same bundle either way—the host controls which capabilities are available.
Start building today