🚀 Curated resources for the agentic commerce protocol landscape — UCP, AP2, A2A, x402, ACP, MPP, trust rails, and interop standards.
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Last updated: 2026-03-23
- Official Documentation
- Specifications & Whitepapers
- Developer Tools & Starters
- Ecosystem & Partners
- News & Analysis
- Videos & Tutorials
- Community
- UCP Official Site — Protocol overview, spec, tutorials, and guides
- Google Developers: UCP Guide — Integration guide for merchants
- UCP GitHub Repository — Specification and documentation
- Under the Hood: UCP (Google Developers Blog) — Technical deep dive (Jan 2026)
- UCP Launch Announcement (Google Blog) — NRF 2026 announcement
- Shopify Engineering: Building UCP — Architecture and layered protocol design
- UCP and AP2 — How UCP integrates with AP2 for secure payments (see "UCP and AP2" section on site)
- UCP Updates (Mar 2026) — Multi-item carts, catalog queries, identity linking
- AP2 Protocol Documentation — Overview, mandate types, A2A/MCP relationships, and integrations
- AP2 Specification
- AP2 GitHub Repository — Spec, Python & Android samples
- Google Cloud AP2 Announcement
- AP2 Roadmap — See roadmap section on official site
- AP2 Partners — See partners section on official site
- AP2 and UCP — How AP2 provides the payment mandate layer for UCP
- A2A Protocol Site — Official documentation and specification
- Announcing Version 1.0 — v1.0 release with enterprise features, signed agent cards, multi-tenancy
- What's New in v1.0 — Migration guide from v0.3 to v1.0
- A2A Specification — Full protocol spec (JSON-RPC 2.0 over HTTP, gRPC, SSE)
- A2A GitHub Repository
- A2A Samples
- A2A x402 Extension — Payment extension for A2A using x402
- A2A Project (Linux Foundation)
- ADK A2A Guides
| Language | Repository | Status |
|---|---|---|
| Python | a2aproject/a2a-python | Stable (v0.3); v1.0 alpha in 1.0-dev branch |
| JavaScript | a2aproject/a2a-js | Stable |
| Go | a2aproject/a2a-go | Stable |
| Java | a2aproject/a2a-java | Stable |
| .NET | a2aproject/a2a-dotnet | Preview (Microsoft Foundry blog) |
- x402.org — Protocol homepage
- x402 Developer Docs — Core concepts, quickstarts, guides (docs.x402.org / Mintlify)
- x402 GitHub Repository — Spec, SDKs (TypeScript, Python, Go), and examples
- x402 Whitepaper (PDF)
- Quickstart for Buyers
- Quickstart for Sellers
- MCP Server with x402 — Guide for monetizing MCP tools with x402
- Migration Guide (v1 → v2) — Standardized CAIP identifiers, modular SDK, new headers
- x402 V2 Launch Post
- Cloudflare Agents SDK: x402 — Built-in x402 support in Cloudflare Workers
- Cloudflare Blog: x402 Foundation — x402 Foundation announcement with Coinbase
Note: The ACP spec is currently in beta and uses date-based version snapshots (2025-09-29, 2025-12-12, 2026-01-16, 2026-01-30).
- ACP Spec Site — Protocol overview and interactive demo
- ACP: Get Started (OpenAI)
- ACP: Key Concepts — Protocol page on OpenAI Developers
- ACP: Product Feeds — Product feed spec for merchant integration
- ACP: Agentic Checkout Spec — Checkout flow and endpoints
- ACP: Delegated Payment Spec — Shared Payment Token and PSP integration
- ACP Spec (GitHub) — Spec, RFCs, examples, changelog
- OpenAI: Buy it in ChatGPT — Instant Checkout launch post
- Stripe: Integrate the ACP — RESTful or MCP server implementation guide
- Stripe: Shared Payment Token — Payment primitive for agentic flows
- Stripe Blog: Developing an Open Standard for Agentic Commerce
- MPP Official Site — Protocol overview, SDKs, and quickstart
- Stripe: Machine Payments with MPP — Implementation docs (crypto + fiat via PaymentIntents)
- Stripe Blog: Introducing MPP — Launch post (Mar 2026)
- Cloudflare Agents Docs: MPP — MPP integration in Cloudflare Workers
- IETF Draft: Payment HTTP Authentication Scheme — See spec link on mpp.dev
MPP and x402: MPP is backwards-compatible with x402. The core x402 exact-payment flows map directly onto MPP's
chargeintent, so MPP clients can consume existing x402 services without modification. MPP additionally supportssession(streaming/pay-as-you-go) payments, recurring payments, and microtransactions across stablecoins, cards, and bank transfers.
- Model Context Protocol (MCP) — Spec & Docs — Standard for AI agent tool interoperability
- MCP Specification (GitHub) — Protocol spec repository
- MCP Registry (Preview) — GitHub MCP Registry for discovering MCP servers
- Web Bot Auth — Architecture Draft (IETF) — Agent identity via HTTP Message Signatures
- Web Bot Auth — Directory Draft (IETF) — Directory for verified bot identities
- Web Bot Auth (Cloudflare Developer Docs)
- ZKProofport — Zero-knowledge proof generation for AI agent identity. Lets agents prove Coinbase KYC, Country, Google OIDC, Google Workspace, or Microsoft 365 affiliation via x402-paid TEE proving on Base. ERC-8004 registered, A2A compatible. NPM:
@zkproofport-ai/mcp. Reference app: OpenStoa (1st place — The Synthesis Hackathon 2026)
- A2A v1.0 Specification
- AP2 Specification
- UCP Specification — Full spec at ucp.dev
- ACP Spec (GitHub) — Versioned snapshots (2025-09-29 through 2026-01-30)
- MPP Overview & Spec — Protocol specification and payment flow documentation
- IETF Payment HTTP Authentication Scheme — See spec link on mpp.dev
- "Towards Multi-Agent Economies: A2A + x402 Micropayments" — Proposes ledger-anchored identities with x402 for A2A micropayments
- UCP GitHub Repository — Spec, SDKs (Python, JavaScript), and reference implementations
- UCP Python Sample — See
samples/in the repo - Google Merchant UCP Integration Guide
- Quickstart for Sellers
- Quickstart for Buyers
- MCP Server with x402
- QuickNode — Using x402 for Paywalls
- Crossmint x402 Starter
- x402 Wallet for Claude Desktop — Claude Desktop extension with x402 USDC payments on Stellar and Base. Automatic 402 handling with configurable spending limits.
- PoolPulse — x402-payable DeFi execution signals API on Base. CLMM slippage, MEV scoring, routing hints for 33 Uniswap V3 + Aerodrome pools. Built with Hono + x402/hono. Pay per call ($0.001–$0.25 USDC). (OpenAPI, Examples)
- x402 Monorepo (GitHub) —
@x402/core,@x402/evm,@x402/svm,@x402/axios,@x402/fetch,@x402/express,@x402/hono,@x402/next,@x402/paywall - x402 Rust crates + Facilitator
- x402-proxy —
curlfor x402 paid APIs. Auto-pays HTTP 402 responses with USDC, with MCP stdio proxy for AI agents
- MPP SDKs — Official TypeScript SDK (
mppx) with middleware for Hono, Express, Next.js, Elysia - Stripe: Machine Payments with MPP — Implementation with PaymentIntents
- A2A Samples Repository — Hello-world, multi-agent, and framework-specific examples
- A2A Inspector — Validate your A2A agent
- Agents SDK Overview
- x402 in Agents SDK — Built-in x402 support
- MPP in Agents SDK — Built-in MPP support
- Cloudflare Blog: x402 Foundation
- OpenAI Agents SDK — MCP
- Stripe MCP Server — Stripe's MCP tools for agentic commerce
Co-developed by Google and Shopify. Endorsed by 20+ partners including Etsy, Wayfair, Target, Walmart, Adyen, American Express, Best Buy, Flipkart, Macy's Inc., Mastercard, Stripe, The Home Depot, Visa, and Zalando. (Source: Google Blog, Jan 2026)
Officially reported supporters include Shopify, Etsy, Salesforce, Mastercard, PayPal, American Express, Adyen, Worldpay, and 60+ partners total. (Source: AP2 Protocol site)
Cloudflare + Coinbase coordinating adoption of x402. The Agents SDK and MCP servers support x402 out of the box. x402 v2 adds modular payment scheme support for EVM and Solana networks.
OpenAI + Stripe co-developed ACP. Currently live with Instant Checkout in ChatGPT (US). Initial merchant partners include Etsy (live) and Shopify merchants (rolling out). ACP is open to any PSP — Stripe is the first with its Shared Payment Token. The spec is in beta with active iteration. (Source: OpenAI)
Stripe + Tempo Labs (Paradigm) co-authored MPP. Design partners include Anthropic, DoorDash, Mastercard, Nubank, OpenAI, Ramp, Revolut, Shopify, Standard Chartered, and Visa. Cloudflare supports MPP in its Agents SDK. (Source: Stripe Blog, Mar 2026)
Visa's Trusted Agent Protocol and Mastercard's Agent Pay both leverage Web Bot Auth for cryptographically signed agent identity during browse and payment flows.
- agenteconomy.to — Real-time dashboard tracking AI agent on-chain payment activity across x402, ERC-8004, ERC-8183 (Virtuals ACP), and MPP (Stripe/Tempo) on 8 chains. Aggregated event counter, chain distribution, facilitator share, and time-series charts. Data refreshes every 6 hours. (source)
- Visa — Trusted Agent Protocol
- Mastercard — Agent Pay; acquired BVNK for stablecoin infrastructure
- PayPal — AP2 support; upcoming UCP payment method
- American Express — AP2 partner, UCP endorser
- Adyen — AP2 integration, UCP endorser
- Worldpay — AP2 support
- Stripe — ACP co-creator, MPP co-author, UCP endorser
- Google Cloud — AP2 creator, UCP co-developer
- OpenAI — ACP co-creator (with Stripe)
- Anthropic — MPP design partner
- Shopify — UCP co-developer, AP2 & ACP partner
- Coinbase — x402 creator, AP2 partner
- Tempo Labs — MPP co-author (Paradigm-backed, payments-optimized L1)
- Google Blog: New tech and tools for retailers (NRF 2026)
- Google Developers Blog: Under the Hood of UCP
- UCP Updates: Multi-item carts, catalog, identity linking (Mar 2026)
- A2A: Announcing Version 1.0 — Enterprise features, signed agent cards, multi-tenancy
- TechCrunch: Google launches new protocol for agent-driven purchases
- Axios: Google's AP2 aims to boost trust in agent shopping
- Digital Commerce 360: AP2 gains support from Shopify, Etsy
- Reuters: OpenAI partners with Etsy, Shopify for ChatGPT checkout
- AP News: OpenAI Instant Checkout coverage
- Stripe Blog: Developing an Open Standard for Agentic Commerce
- Constellation Research: Google's AP2 fleshes out AI agent commerce
- Finextra Deep Dive: Google's AP2 explained
- PYMNTS: Google unveils payment protocol for AI-driven commerce
- Digital Commerce 360: OpenAI expands agentic commerce push (Feb 2026)
- Intro to Google Agent Payments Protocol (AP2) — Beginner-friendly introduction
- AP2 Overview & Ecosystem Breakdown — Comprehensive ecosystem analysis
- Technical Review: AP2 Code Walkthrough (Kotlin) — Code implementation review
- AP2 Core Concept: Signed Authorization & Accountability — Short-form explanation
- After MCP & A2A, Meet AP2 — Protocol evolution overview
- x402 Deep Dive & Demos — Technical walkthrough
- x402 Short Explainer — Quick overview
- OpenAI: Buy it in ChatGPT (ACP) — Official product demo
- A2A Protocol Short Course (DeepLearning.AI) — Built with Google Cloud and IBM Research (see repo for link)
- Google Developers Community: AP2 Introduction
- x402 Community FAQ — FAQ & Discord links
- A2A GitHub Discussions
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UCP (Universal Commerce Protocol) is an open standard co-developed by Google and Shopify for agentic commerce across the full shopping journey — discovery, checkout, identity linking, and order management. UCP is transport-agnostic (REST, MCP, A2A) and compatible with AP2 for secure payment mandates. Launched January 2026 at NRF.
AP2 (Agent Payments Protocol) is Google's open protocol for agent-driven payments with verifiable authorization (mandates) and accountability. Its current core focus is card-based payments with mandate-driven authorization. AP2 serves as the payment layer within UCP.
A2A (Agent-to-Agent Protocol) is an open standard under the Linux Foundation for agent interoperability — discovery, communication, and task delegation across agent frameworks and vendors. The v1.0 release (2026) added enterprise features including signed agent cards, multi-tenancy, and version negotiation. The TSC includes AWS, Cisco, Google, IBM Research, Microsoft, Salesforce, SAP, and ServiceNow.
x402 is an open payment standard built on HTTP 402 for machine-native, internet-native payments. Created by Coinbase and coordinated with Cloudflare via the x402 Foundation. Supports stablecoins on EVM and Solana networks. The v2 release (late 2025) introduced CAIP-based identifiers, a modular SDK architecture, and standards-compliant payment headers.
ACP (Agentic Commerce Protocol) is an open standard co-developed by OpenAI and Stripe for connecting buyers, AI agents, and businesses to complete purchases. Powers Instant Checkout in ChatGPT. Currently in beta with date-based version snapshots. Designed to work with any PSP — Stripe provides the first implementation via Shared Payment Token.
MPP (Machine Payments Protocol) is an open standard co-authored by Tempo Labs and Stripe for machine-to-machine payments over HTTP 402. Supports stablecoins, cards, and bank transfers. Offers charge (one-off) and session (streaming micropayment) intents. Backwards-compatible with x402. Based on an IETF-proposed Payment HTTP Authentication Scheme. Launched March 2026.
Trusted Agent Protocol (Visa) / Agent Pay (Mastercard) help merchants and networks recognize cryptographically verified AI agents during browse and pay flows, built on Web Bot Auth (IETF drafts).
This list is released under CC0 1.0 (Public Domain). No rights reserved.
Keywords: ucp ap2 agent-payments agentic-commerce a2a x402 acp mpp machine-payments-protocol trusted-agent-protocol agent-pay web-bot-auth mcp stablecoins verifiable-credentials google-cloud coinbase stripe openai tempo
