> ## Documentation Index
> Fetch the complete documentation index at: https://learn.orbexa.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Full-stack developer guide to AI commerce APIs

> Developer learning path — go from OTR API integration to full UCP/ACP/MCP protocol implementation in about 2 hours of hands-on work.

# Full-Stack Developer Path

From understanding the OTR trust layer to implementing every commerce protocol. Complete API reference and code examples throughout.

**Estimated time**: \~2 hours

## Learning Steps

<Steps>
  <Step title="OTR Protocol Overview">
    Read [Book 2, Chapters 1-2: Why AI Agents Need a Trust Layer](/en/book-2/ch1-why-trust-layer)

    Understand why AI agents require a trust layer and how OTR's four-tier architecture works.
  </Step>

  <Step title="OTR API Reference">
    Read [Book 2, Chapter 6: REST API](/en/book-2/ch6-rest-api)

    Call `GET /api/otr/verify/{domain}` to query any domain's trust score. Full endpoint documentation and integration examples.
  </Step>

  <Step title="OTR MCP Server">
    Read [Book 2, Chapter 7: MCP Server](/en/book-2/ch7-mcp-server)

    Enable AI applications like Claude and ChatGPT to call OTR trust queries directly.
  </Step>

  <Step title="UCP — Universal Commerce Protocol">
    Read [Book 3: UCP Protocol Deep Dive](/en/book-3/index)

    The product discovery protocol co-created by Google and Shopify. Covers checkout, identity linking, and order management.
  </Step>

  <Step title="ACP — Agent Commerce Protocol">
    Read [Book 4: ACP Protocol Deep Dive](/en/book-4/index)

    The AI agent checkout protocol initiated by Stripe. Product catalog submission and ChatGPT integration.
  </Step>

  <Step title="MCP — Model Context Protocol">
    Read [Book 5: MCP Protocol Deep Dive](/en/book-5/index)

    Build an MCP Server so AI applications can call your commerce tools — product search, order lookup, returns processing, and more.
  </Step>

  <Step title="AI-SEO Technical Implementation">
    Read the technical chapters from Book 6:

    * [Schema.org in Practice](/en/book-6/ch3-schema-org) — JSON-LD code examples
    * [llms.txt Authoring Guide](/en/book-6/ch6-llms-txt) — Deployment methods
    * [agent.json Service Declaration](/en/book-6/ch7-agent-json) — Capability declaration specification
  </Step>
</Steps>