Build MCP apps once, run them anywhere
MCP apps let you put real UI inside AI conversations — not just text, but things people can actually interact with. Build and preview locally with hot reload, then export once for any host.
Try the workbench
Preview your app in real time, mock tool calls, and export a production-ready bundle — all from your browser.
Best on desktop
Open this page on a desktop browser to try the interactive demo.
Everything you need to ship MCP apps
Build it, preview it, export it. One toolchain for whatever you're shipping.
Hot reload across every screen size — desktop, tablet, and mobile.
Stub out tool calls with JSON responses. Test success paths, errors, and edge cases — no backend needed.
Includes an MCP server template. Run frontend and tools with a single command.
Export a deployable widget bundle with one command. Use `--inline` for a single-file build.
Preview inline, picture-in-picture, and fullscreen — exactly as it appears in Claude or ChatGPT.
One API surface for MCP hosts and ChatGPT extensions, with capabilities detected at runtime.
Know what works where
Your app runs inside the host's conversation window. Different hosts support different things — detect what's available and adapt.
Export and ship
Ship one bundle that works in Claude, ChatGPT, or any MCP-compatible client.
Deploy export/widget/ to any static host, then point export/manifest.json at the hosted URL and register with your target host. The same bundle runs on MCP hosts like Claude and as a ChatGPT extension. Export emits index.html, widget.js, and widget.css by default — add --inline for single-file HTML. The host decides which capabilities your app can use.
Start building today