Build MCP apps once, run them anywhere
Build locally with hot reload. Export once for any MCP host. Optional ChatGPT extension features are detected at runtime.
Try the workbench
A local simulator for MCP apps and optional ChatGPT extensions. 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 deployable widget bundle (index.html + widget.js/widget.css) with optional --inline output.
Preview inline, PiP, and fullscreen. See exactly how it looks in target hosts.
MCP-first bridge with optional ChatGPT extensions, feature-detected at runtime.
Know what works where
One API surface with capability gating across MCP hosts and optional ChatGPT extensions.
Export and ship
Your production-ready bundle, ready for MCP hosts like Claude, with optional ChatGPT extensions.
Deploy export/widget/ to any static host, then update export/manifest.json with the hosted URL and register it with your target host. The same widget works across MCP hosts (for example, Claude) and ChatGPT extensions. By default export emits index.html, widget.js, widget.css, with optional --inline for single-file HTML. It’s the same app either way; the host controls which capabilities are available.
Start building today