# A2UI Atomic Catalog — API

Scoped context for the REST surface. Full manual: https://a2uicatalog.ai/llms.txt

## Render a payload

POST https://a2uicatalog.ai/api/render
Content-Type: application/json
{"title":"Demo","theme":"light","blocks":[{"type":"stat_card","value":"1,234","label":"Daily users"}]}

Returns a complete self-contained HTML page. No MCP, no connector, no deployment.
Optional ?surface=web|mcp-apps|google-apps-script-web|google-meet-stage applies that
surface's declared compatibility policy: atoms marked degraded_on render and are named
in X-A2UI-Degraded; atoms marked incompatible_on are replaced by a visible note and
named in X-A2UI-Incompatible. pdf, email and google-chat return 400 — this endpoint
emits HTML.

Limits: 256 KB body, 300 blocks, 12 levels of nesting, 50 requests/day. Cache hits are free.

## Natural language to atoms

POST https://a2uicatalog.ai/api/compose  {"prompt":"a dashboard with daily users and a bar chart"}
Returns candidate atom blocks. 20 requests/day.

## Search the vocabulary

GET https://a2uicatalog.ai/ask?q=<question>   60 requests/day.

## Declared data proxy

GET https://a2uicatalog.ai/api/data/{source}  Sources declared in atoms/data-sources.yaml.

## Contract

- Docs search (MCP): https://a2uicatalog.ai/mcp-docs — search_docs(query)/list_docs(), a
  separate MCP identity from the product server at /mcp.
- OpenAPI 3.1: https://a2uicatalog.ai/openapi.json
- Versioning: header-based (X-API-Version), not URL path. https://a2uicatalog.ai/versioning.md
- Auth: none required. https://a2uicatalog.ai/auth.md
- Pricing: free. https://a2uicatalog.ai/pricing.md