Protocol directory
Agentic commerce protocol directory
A maintained directory of the core protocols used around agentic commerce. The Atlas is not the primary specification for any protocol; use this page to understand the layer, role, maintainer, and status, then follow the official source for implementation details.
Machine-readable version: /data/protocols.json. Last checked:
2026-06-29.
| Protocol | Layer | Maintainer and status | Source | Atlas guide |
|---|---|---|---|---|
| ACP Agentic Commerce Protocol | Commerce semantics | OpenAI, Stripe, Meta beta | Official source | Read guide |
| UCP Universal Commerce Protocol | Commerce semantics | Google and the UCP Tech Council (Shopify, Etsy, Target, Wayfair, plus Amazon, Meta, Microsoft, Salesforce, Stripe from April 2026) launched | Official source | Read guide |
| AP2 Agent Payments Protocol | Payment authorization | FIDO Alliance (originated at Google) pre-production | Official source | Read guide |
| MCP Model Context Protocol | Discovery | Anthropic (donated to a foundation, Dec 2025) widely adopted | Official source | Read guide |
| A2A Agent-to-Agent | Agent coordination | Linux Foundation (originated at Google) v1.0 | Official source | Read guide |
| x402 x402 | Settlement | Coinbase (x402 Foundation, under the Linux Foundation) live | Official source | Read guide |
| MPP Machine Payments Protocol | Settlement | Stripe and Tempo live | Official source | Read guide |
How to read the layers
- Discovery: how agents find tools, data, and capabilities.
- Commerce semantics: how shopping, cart, checkout, and post-purchase actions are represented.
- Payment authorization: how user intent and delegated authority are recorded.
- Settlement: how software pays for services, API calls, or other resources.
- Agent coordination: how agents communicate and delegate work to one another.
Use boundaries
This directory is an orientation layer. It is useful for comparison, discovery, and citation, but implementation-critical decisions should be checked against the official source linked for each protocol.