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Documentation Index

Fetch the complete documentation index at: https://docs.skybridge.tech/llms.txt

Use this file to discover all available pages before exploring further.

The OpenAI Apps SDK is the ChatGPT runtime layer for ChatGPT Apps, announced in October 2025. ChatGPT supports the MCP Apps UI model, and also provides window.openai for compatibility and ChatGPT-specific extensions.

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View Rendering Flow

Here’s what happens when ChatGPT renders a view:
  1. User asks ChatGPT to perform an action (e.g., “Show me flight options to Paris”)
  2. ChatGPT calls your MCP tool (e.g., search_flights)
  3. Your tool returns a result with data and a reference to a UI resource
  4. ChatGPT fetches the resource (your compiled React component) and renders it in an iframe
  5. The view is hydrated with your tool’s structuredContent and _meta properties
ChatGPT Apps Rendering Flow

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The window.openai API

Views run inside an iframe and have access to a special window.openai global. In ChatGPT, this acts as a compatibility layer plus an extension surface for host-specific features:
APIDescription
toolInputArguments supplied when the tool was invoked
toolOutputYour structuredContent — initial data passed from your tool
toolResponseMetadataThe _meta payload; only the view sees it, never the model
viewState / setViewState()Persist UI state across interactions
callTool()Trigger additional tool calls from the UI
sendFollowUpMessage()Send messages back into the chat
requestDisplayMode()Request inline, PiP, or fullscreen display
requestModal()Open a modal window outside the iframe
uploadFile()Upload files to host-managed storage
getFileDownloadUrl()Get download URLs for uploaded files
openExternal()Open external URLs safely
setOpenInAppUrl()Set URL for the “Open in <App>” button in fullscreen mode
This API is powerful but low-level and imperative—which is where Skybridge comes in.

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Skybridge Hook Mapping

Skybridge wraps the raw window.openai API with React hooks:
Raw APISkybridge HookPurpose
window.openai.toolInput, toolOutput, toolResponseMetadatauseToolInfo()Access tool input, output, and _meta
window.openai.widgetState and window.openai.setWidgetStateuseViewState()Persistent view state
window.openai.callTool()useCallTool()Make additional tool calls
window.openai.sendFollowUpMessage()useSendFollowUpMessage()Send follow-up messages
window.openai.openExternal()useOpenExternal()Open external URLs
window.openai.view and window.openai.requestModal()useRequestModal()Request modal display
window.openai.theme, maxHeight, safeAreauseLayout()Theme, max height, safe area insets
window.openai.locale, userAgentuseUser()Locale and device/capabilities
window.openai.displayMode and window.openai.requestDisplayModeuseDisplayMode()Access/change display mode
window.openai.uploadFile(), getFileDownloadUrl()useFiles()Upload and download files
window.openai.setOpenInAppUrl()useSetOpenInAppUrl()”Open in App” button URL in fullscreen
window.openai.requestClose()useRequestClose()Close the view from the UI (e.g. user dismisses)

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Skybridge Apps SDK Exclusive Features

These features are only available in ChatGPT and not supported in MCP Apps:

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File Operations

Upload and download files with host-managed storage: 
import { useFiles } from "skybridge/web";

function View() {
  const { upload, getDownloadUrl } = useFiles();

  const handleUpload = async (file: File) => {
    const { fileId } = await upload(file);
    const { downloadUrl } = await getDownloadUrl({ fileId });
    // Use downloadUrl...
  };

  return <input type="file" onChange={handleUpload} />;
}

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Open in App URL

Set a URL for the “Open in App” button that appears in fullscreen mode: 
import { useSetOpenInAppUrl } from "skybridge/web";

function View() {
  const { setOpenInAppUrl } = useSetOpenInAppUrl();

  useEffect(() => {
    setOpenInAppUrl("https://myapp.com/view/123");
  }, []);

  return <div>View content</div>;
}

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Testing in ChatGPT

Please see the Test Your App guide for more information.
ChatGPT has aggressive caching. Use DevTools for fast iteration, then test in ChatGPT for final validation. See Fast Iteration.