{
  "generated": "2026-10-27",
  "note": "Protocol dataset for agentwillpay.com. Each entry carries version history, adoption signals, settlement rails, regions and sources. No scores, no rankings. Dates marked \"unverified\" could not be confirmed in sources consulted; no date or claim in this file is invented.",
  "protocols": [
    {
      "adoption_signals": [
        {
          "date": "2025-09-23",
          "signal": "Coinbase and Cloudflare announce plans for an x402 Foundation.",
          "source": "https://yellow.com/learn/ai-agent-payments-explained-x402-ap2-stablecoins"
        },
        {
          "date": "2026-04-02",
          "signal": "Linux Foundation formalizes the x402 Foundation.",
          "source": "https://eco.com/support/en/articles/14839402-x402-protocol-explained?ref=blockhead.co"
        },
        {
          "date": "2026-06",
          "signal": "Chainalysis counts over 100 million cumulative x402 transactions on Base through Q1 2026, noting much of the late-2025 surge was meme-coin activity rather than agents buying services.",
          "source": "https://www.meshpay.com/blog/agentic-payment-protocols-compared"
        },
        {
          "date": "2026-07-14",
          "signal": "Linux Foundation operationally launches the x402 Foundation with 40 member organizations; premier members include Visa, Mastercard, American Express, Stripe, Adyen, Fiserv, Google, Amazon Web Services, Shopify, Cloudflare and Coinbase.",
          "source": "https://www.linuxfoundation.org/press/linux-foundation-announces-operational-launch-of-x402-foundation-to-standardize-internet-native-payments-for-ai-agents-and-applications"
        }
      ],
      "id": "x402",
      "name": "x402",
      "owner": "x402 Foundation (Linux Foundation); originally authored by Coinbase",
      "regions": [
        "Global (permissionless; chain-based, no jurisdictional restriction stated)"
      ],
      "settlement_rails": [
        "Stablecoins (USDC primary; EURC; XRP and RLUSD via Ripple)",
        "EVM chains and Solana",
        "Cards (within Foundation scope; live traffic is stablecoin-denominated)"
      ],
      "sources": [
        {
          "label": "Linux Foundation press release: operational launch of the x402 Foundation",
          "url": "https://www.linuxfoundation.org/press/linux-foundation-announces-operational-launch-of-x402-foundation-to-standardize-internet-native-payments-for-ai-agents-and-applications"
        },
        {
          "label": "eco.com: x402 Protocol Explained",
          "url": "https://eco.com/support/en/articles/14839402-x402-protocol-explained?ref=blockhead.co"
        },
        {
          "label": "Yellow: AI Agent Payments Explained (x402, AP2, stablecoins)",
          "url": "https://yellow.com/learn/ai-agent-payments-explained-x402-ap2-stablecoins"
        },
        {
          "label": "Concordium: x402 Explained",
          "url": "https://www.concordium.com/article/x402-explained-agentic-payments-identity"
        },
        {
          "label": "inriver: What are AP2, MPP, and x402?",
          "url": "https://www.inriver.com/resources/ap2-mpp-x402-payment-protocols-agent-commerce/"
        }
      ],
      "versions": [
        {
          "date": "2025-05-06",
          "note": "Coinbase launches x402: an open HTTP-native payment protocol that repurposes HTTP 402 Payment Required so a server quotes a price, the client retries with a signed payment authorization, and a facilitator verifies and settles, originally in USDC on Base.",
          "version": "initial release"
        },
        {
          "date": "2025-12-11",
          "note": "Multi-chain by default; switches to PAYMENT-SIGNATURE and PAYMENT-RESPONSE headers, CAIP-2 network identifiers and modular packages; adds wallet-based sessions and dynamic payee routing.",
          "version": "v2"
        }
      ]
    },
    {
      "adoption_signals": [
        {
          "date": "2025-09-16",
          "signal": "Announcement with 60+ partners including Mastercard, PayPal, Coinbase, American Express, Adyen, Etsy, Revolut, Salesforce and Worldpay.",
          "source": "https://yellow.com/learn/ai-agent-payments-explained-x402-ap2-stablecoins"
        },
        {
          "date": "2026-03-05",
          "signal": "Mastercard and Google open-source Verifiable Intent, a cryptographic framework binding consumer identity, spending mandates and transaction outcomes into tamper-resistant records.",
          "source": "https://www.accertify.com/resource/agentic-ai-fraud-and-commerce-dont-panic-but-do-prepare/"
        },
        {
          "date": "2026-04-28",
          "signal": "AP2 donated to the FIDO Alliance; two FIDO technical working groups develop the standards, with chairs including Google, OpenAI, CVS Health, Mastercard and Visa.",
          "source": "https://www.inriver.com/resources/ap2-mpp-x402-payment-protocols-agent-commerce/"
        }
      ],
      "id": "ap2",
      "name": "Agent Payments Protocol (AP2)",
      "owner": "Google; donated to the FIDO Alliance on 2026-04-28",
      "regions": [
        "Global (open specification; 60+ launch organizations)"
      ],
      "settlement_rails": [
        "Payment-method agnostic: AP2 authorizes, it does not settle",
        "Cards (in use today)",
        "Real-time bank transfers (roadmap: UPI, PIX)",
        "Stablecoins (via the a2a-x402 extension)"
      ],
      "sources": [
        {
          "label": "inriver: What are AP2, MPP, and x402?",
          "url": "https://www.inriver.com/resources/ap2-mpp-x402-payment-protocols-agent-commerce/"
        },
        {
          "label": "MeshPay: Agentic Payment Protocols Compared",
          "url": "https://www.meshpay.com/blog/agentic-payment-protocols-compared"
        },
        {
          "label": "Splunk: The Agent Economy",
          "url": "https://www.splunk.com/en_us/blog/artificial-intelligence/the-agent-economy-when-ais-pay-each-other.html"
        },
        {
          "label": "Yellow: AI Agent Payments Explained (x402, AP2, stablecoins)",
          "url": "https://yellow.com/learn/ai-agent-payments-explained-x402-ap2-stablecoins"
        },
        {
          "label": "Forkast: Know Your Agent (trust layer)",
          "url": "https://forkast.news/know-your-agent-how-the-payments-industry-is-building-the-trust-layer-oauth-and-saml-couldnt/"
        }
      ],
      "versions": [
        {
          "date": "2025-09-16",
          "note": "Google announces AP2 with 60+ payments and technology organizations. AP2 is an authorization layer, not a settlement rail: a purchase is represented by signed mandates (Intent Mandate, Cart Mandate, Payment Mandate) carried as W3C Verifiable Credentials. It runs as an extension of the Agent2Agent protocol and the Model Context Protocol.",
          "version": "initial release"
        },
        {
          "date": "2026-04-28",
          "note": "Adds Human Not Present payments (an agent executes a pre-authorized purchase autonomously, within constraints such as price ceilings) and Verifiable Intent (co-developed with Mastercard). Released alongside the donation of the protocol to the FIDO Alliance.",
          "version": "v0.2"
        }
      ]
    },
    {
      "adoption_signals": [
        {
          "date": "2025-04-30",
          "signal": "Launch announcement at Visa Global Product Drop with AI and technology partners named above.",
          "source": "https://www.digitalcommerce360.com/2025/05/06/visa-mastercard-ai-agentic-commerce/"
        },
        {
          "date": "2026-06-10",
          "signal": "At Visa Payments Forum: Agent Score (readiness check for whether agents can navigate and complete tasks on a site), Agentic Directory (registry of Visa-verified agents and merchants), token assurance signal, and a strategic collaboration with OpenAI to enable Visa payments within agentic commerce.",
          "source": "https://techsoma.africa/visa-and-openai-partner-to-build-the-payment-infrastructure-for-ai-agents/"
        },
        {
          "date": "2026-10-20",
          "signal": "First live pilot with BILL and Billtrust: trusted AI agents initiate and complete approved buyer invoice payments end-to-end through supplier portals, using TAP and the Agentic Directory.",
          "source": "https://usa.visa.com/about-visa/newsroom/press-releases.releaseId.22856.html"
        },
        {
          "date": "unverified",
          "signal": "Visa reports Intelligent Commerce live in the United States with transactions taking place; the claim is undated in sources consulted, so no live date is asserted.",
          "source": "https://www.meshpay.com/blog/agentic-payment-protocols-compared"
        }
      ],
      "id": "visa-intelligent-commerce",
      "name": "Visa Intelligent Commerce",
      "owner": "Visa",
      "regions": [
        "United States",
        "Europe",
        "Asia Pacific",
        "Latin America"
      ],
      "settlement_rails": [
        "Visa network (tokenized card credentials)"
      ],
      "sources": [
        {
          "label": "PYMNTS: Visa and OpenAI Unlock Agentic Commerce",
          "url": "https://www.pymnts.com/news/artificial-intelligence/2026/visa-openai-unlock-agentic-commerce/"
        },
        {
          "label": "Digital Commerce 360: Visa opens payment tools for AI agents",
          "url": "https://www.digitalcommerce360.com/2025/05/06/visa-mastercard-ai-agentic-commerce/"
        },
        {
          "label": "HapaKenya: Visa Intelligent Commerce launched",
          "url": "https://hapakenya.com/2025/05/02/visa-intelligent-commerce-launched-to-support-ai-driven-shopping-and-payments/"
        },
        {
          "label": "thesoftix: Agentic Commerce for SMBs in 2026 (Connect, Agent Score, Agentic Directory)",
          "url": "https://thesoftix.com/agentic-commerce-smb-payments-2026/"
        },
        {
          "label": "Visa press release: Visa, BILL and Billtrust first live pilot",
          "url": "https://usa.visa.com/about-visa/newsroom/press-releases.releaseId.22856.html"
        }
      ],
      "versions": [
        {
          "date": "2025-04-30",
          "note": "Network program announced at Visa Global Product Drop: a suite of APIs and a partner program opening the Visa network to AI agents. Components at launch: AI-ready cards (tokenized credentials bound to a permissioned agent context), personalization with consent, spending controls, and transaction signals for risk controls and dispute support. Launch partners included Anthropic, IBM, Microsoft, Mistral AI, OpenAI, Perplexity, Samsung and Stripe. This is a network program, not a wire protocol.",
          "version": "initial launch"
        },
        {
          "date": "2026-04-08",
          "note": "Single integration via the Visa Acceptance Platform, described as network-, protocol- and token-vault-agnostic. Supported agent protocols named by Visa: Trusted Agent Protocol, Machine Payments Protocol (MPP), Agentic Commerce Protocol (ACP) and Universal Commerce Protocol (UCP). Pilot partners named at announcement: Aldar, AWS, Diddo, Highnote, Mesh, Payabli, Sumvin.",
          "version": "Intelligent Commerce Connect"
        }
      ]
    },
    {
      "adoption_signals": [
        {
          "date": "2025-04-29",
          "signal": "Launch announcement (Mastercard Newsroom).",
          "source": "http://newsroom.mastercard.com/news/press/2025/april/mastercard-unveils-agent-pay-pioneering-agentic-payments-technology-to-power-commerce-in-the-age-of-ai/"
        },
        {
          "date": "2025-09",
          "signal": "Citi and US Bank cardholders gain first access (pilot).",
          "source": "https://eco.com/support/en/articles/14839401-agentic-payments-how-ai-agents-pay"
        },
        {
          "date": "2025-10-27",
          "signal": "PayPal joins the acceptance side, covering PayPal-accepting merchants.",
          "source": "https://eco.com/support/en/articles/14839401-agentic-payments-how-ai-agents-pay"
        },
        {
          "date": "2026-03-02",
          "signal": "Europe's first live end-to-end agent payment: Santander and Mastercard complete a controlled-environment transaction on Santander's live payments infrastructure.",
          "source": "https://www.mastercard.com/news/europe/en/newsroom/press-releases/en/2026/santander-and-mastercard-complete-europe-s-first-live-end-to-end-payment-executed-by-an-ai-agent/"
        },
        {
          "date": "2026-09-30",
          "signal": "Agent Pay Trust Framework published (white paper 'Trust for agentic commerce'): identity, intent, controls, trusted execution, intelligence; plus new trust and intelligence services including an AI-initiated probability score in US testing.",
          "source": "https://s25.q4cdn.com/479285134/files/doc_news/Mastercard-Advances-Agentic-Commerce-With-New-Trust-and-Intelligence-Services-2026.pdf"
        }
      ],
      "id": "mastercard-agent-pay",
      "name": "Mastercard Agent Pay",
      "owner": "Mastercard",
      "regions": [
        "United States",
        "Europe"
      ],
      "settlement_rails": [
        "Mastercard network (Agentic Tokens on card rails)"
      ],
      "sources": [
        {
          "label": "Mastercard Newsroom: Agent Pay launch",
          "url": "http://newsroom.mastercard.com/news/press/2025/april/mastercard-unveils-agent-pay-pioneering-agentic-payments-technology-to-power-commerce-in-the-age-of-ai/"
        },
        {
          "label": "Mastercard Newsroom: Santander Europe first live agent payment",
          "url": "https://www.mastercard.com/news/europe/en/newsroom/press-releases/en/2026/santander-and-mastercard-complete-europe-s-first-live-end-to-end-payment-executed-by-an-ai-agent/"
        },
        {
          "label": "Mastercard Investor Relations: Trust and Intelligence Services (2026-09-30)",
          "url": "https://s25.q4cdn.com/479285134/files/doc_news/Mastercard-Advances-Agentic-Commerce-With-New-Trust-and-Intelligence-Services-2026.pdf"
        },
        {
          "label": "eco.com: Agentic Payments (Agent Pay rollout)",
          "url": "https://eco.com/support/en/articles/14839401-agentic-payments-how-ai-agents-pay"
        }
      ],
      "versions": [
        {
          "date": "2025-04-29",
          "note": "Agentic Payments Program announced. Mastercard Agentic Tokens build on existing tokenization (mobile contactless, secure card-on-file, Payment Passkeys): a tokenized credential bound to a specific agent, merchant scope and consent policy, carrying agent identity into the transaction record. Collaborations named at launch: Microsoft, IBM watsonx Orchestrate, Braintree, Checkout.com.",
          "version": "launch"
        },
        {
          "date": "2025-11",
          "note": "Full US availability for cardholders. Month precision only; the exact day was not verified in sources consulted. Citi and US Bank cardholders entered a pilot in September 2025; PayPal joined the acceptance side on October 27, 2025.",
          "version": "US general availability"
        }
      ]
    },
    {
      "adoption_signals": [
        {
          "date": "2026-06-10",
          "signal": "Launch with 30+ initial participants including Adyen, Stripe, Checkout.com, Cloudflare, Coinbase, Ripple, Polygon, Solana Foundation, Tempo, Turnkey, Crossmint and Aave Labs.",
          "source": "https://agenticplug.ai/blog/what-is-mastercard-agent-pay-for-machines"
        },
        {
          "date": "2026-10-20",
          "signal": "Early access opened at Cloudflare Connect; end-to-end pilots previously run with Cloudflare, Coinbase, Base, Ant International, BVNK and AIsa. Coverage continues to describe the program as pilot stage, not commercially available.",
          "source": "https://cryptobriefing.com/mastercard-agent-pay-machines-early-access/"
        }
      ],
      "id": "mastercard-agent-pay-for-machines",
      "name": "Mastercard Agent Pay for Machines (AP4M)",
      "owner": "Mastercard",
      "regions": [
        "Global (participants span acquirers, rails and wallets; early access to developers)"
      ],
      "settlement_rails": [
        "Cards",
        "Bank accounts",
        "Stablecoins"
      ],
      "sources": [
        {
          "label": "Agentic Plug: What Is Mastercard Agent Pay for Machines (AP4M)?",
          "url": "https://agenticplug.ai/blog/what-is-mastercard-agent-pay-for-machines"
        },
        {
          "label": "MeshPay: Agentic Payment Protocols Compared",
          "url": "https://www.meshpay.com/blog/agentic-payment-protocols-compared"
        },
        {
          "label": "Crypto Briefing: Mastercard opens early access at Cloudflare Connect",
          "url": "https://cryptobriefing.com/mastercard-agent-pay-machines-early-access/"
        },
        {
          "label": "PaySpace Magazine: Mastercard Opens Early Access to Agent Pay for Machines",
          "url": "https://payspacemagazine.com/news/mastercard-opens-early-access-to-agent-pay-for-machines-for-ai-agent-payments/"
        }
      ],
      "versions": [
        {
          "date": "2026-06-10",
          "note": "Network service for high-frequency, micro-value machine-to-machine payments at machine speed, without a human approving each payment. Capabilities: credentialing, permissioning, transacting, settling; guaranteed multi-rail settlement across cards, accounts and stablecoins; recipients paid in their preferred currency (fiat or stablecoin).",
          "version": "launch"
        },
        {
          "date": "2026-10-20",
          "note": "Opened to early-access developers at Cloudflare Connect: buyer- and seller-side APIs, developer toolkit, testing sandbox. Demonstration: an agent for marketing agency Hype made 9 payments to 2 merchants (AIsa research, Cloudflare AI Gateway images) under one approved budget, running on x402.",
          "version": "early access"
        }
      ]
    },
    {
      "adoption_signals": [
        {
          "date": "2025-10-14",
          "signal": "Launch with Cloudflare. Early implementers named: Adyen, Ant International, Checkout.com, Coinbase, Fiserv, Microsoft, Shopify, Stripe, Worldpay.",
          "source": "https://eco.com/support/en/articles/14839401-agentic-payments-how-ai-agents-pay"
        },
        {
          "date": "2026-04-08",
          "signal": "Supported by Visa Intelligent Commerce Connect alongside MPP, ACP and UCP.",
          "source": "https://thesoftix.com/agentic-commerce-smb-payments-2026/"
        },
        {
          "date": "2026-10-20",
          "signal": "Used in the Visa/BILL/Billtrust live pilot: the BILL Payment Agent registers via TAP and the Agentic Directory, and Billtrust authenticates the agent at supplier portals via TAP.",
          "source": "https://usa.visa.com/about-visa/newsroom/press-releases.releaseId.22856.html"
        }
      ],
      "id": "tap",
      "name": "Trusted Agent Protocol (TAP)",
      "owner": "Visa, co-developed with Cloudflare",
      "regions": [
        "Global (open specification)"
      ],
      "settlement_rails": [
        "None (identity layer; gates card rails rather than settling)"
      ],
      "sources": [
        {
          "label": "eco.com: Agentic Payments (TAP section)",
          "url": "https://eco.com/support/en/articles/14839401-agentic-payments-how-ai-agents-pay"
        },
        {
          "label": "Forkast: Trusted Agent Protocol (TAP) glossary",
          "url": "https://forkast.news/glossary/trusted-agent-protocol/"
        },
        {
          "label": "Forkast: Know Your Agent (trust layer)",
          "url": "https://forkast.news/know-your-agent-how-the-payments-industry-is-building-the-trust-layer-oauth-and-saml-couldnt/"
        },
        {
          "label": "Visa press release: Visa, BILL and Billtrust first live pilot",
          "url": "https://usa.visa.com/about-visa/newsroom/press-releases.releaseId.22856.html"
        }
      ],
      "versions": [
        {
          "date": "2025-10-14",
          "note": "Public specification on GitHub. TAP is an identity layer, not a payment rail: the agent signs its identity (and a session-bound nonce) into HTTP request headers using public-key cryptography (RFC 9421 HTTP Message Signatures, Ed25519); the merchant verifies against a Visa-operated directory of agent public keys. Signals carried: agent intent, consumer recognition, payment information. Cloudflare is the reference bot-management implementation.",
          "version": "initial release"
        }
      ]
    },
    {
      "adoption_signals": [
        {
          "date": "2025-09-29",
          "signal": "Release; ChatGPT Instant Checkout live in the US at launch.",
          "source": "https://www.meshpay.com/blog/agentic-payment-protocols-compared"
        },
        {
          "date": "2026-03-04",
          "signal": "OpenAI scales back Instant Checkout: purchases complete on merchant sites or merchant-built ChatGPT apps, with ChatGPT focused on product discovery. Specification remains in beta.",
          "source": "https://www.novastacks-ai.com/blog/ucp-acp-agentic-commerce-explained"
        }
      ],
      "id": "acp",
      "name": "Agentic Commerce Protocol (ACP)",
      "owner": "Stripe and OpenAI (specification maintained by OpenAI and Stripe; Stripe documentation also credits Meta as a creator)",
      "regions": [
        "United States (ChatGPT Instant Checkout at launch)"
      ],
      "settlement_rails": [
        "Cards (via the merchant's existing payment provider; Stripe)"
      ],
      "sources": [
        {
          "label": "MeshPay: Agentic Payment Protocols Compared",
          "url": "https://www.meshpay.com/blog/agentic-payment-protocols-compared"
        },
        {
          "label": "Splunk: The Agent Economy",
          "url": "https://www.splunk.com/en_us/blog/artificial-intelligence/the-agent-economy-when-ais-pay-each-other.html"
        },
        {
          "label": "Novastacks: UCP vs ACP",
          "url": "https://www.novastacks-ai.com/blog/ucp-acp-agentic-commerce-explained"
        },
        {
          "label": "vreeman.ai: AI commerce protocols (UCP, ACP, AP2, x402)",
          "url": "https://vreeman.ai/commerce"
        }
      ],
      "versions": [
        {
          "date": "2025-09-29",
          "note": "Released under Apache 2.0. Commerce-layer standard for checkout between an AI agent and a merchant: the agent collects the buyer's payment selection and passes a narrowly scoped payment token to the merchant, which charges it through its existing payment provider and remains merchant of record for catalog, pricing, fulfillment and support. Live at launch with ChatGPT Instant Checkout.",
          "version": "initial release"
        }
      ]
    },
    {
      "adoption_signals": [
        {
          "date": "2026-05-19",
          "signal": "Google previews Universal Cart at Google I/O 2026: UCP-powered checkout rolling out across Search and the Gemini app in the US, with Canada, Australia and the UK to follow.",
          "source": "https://fourweekmba.com/ai-google-launches-universal-cart-on-60b-listings-across-gemini/"
        },
        {
          "date": "2026-10-13",
          "signal": "Shopify Shop MCP (UCP over MCP) open to any agent.",
          "source": "https://vreeman.ai/commerce"
        },
        {
          "date": "2026-10-15",
          "signal": "UCP checkout via Google Universal Cart live in the US (AI Mode in Search, Gemini app), with Google Pay checkout or handoff to the merchant cart; merchant stays seller of record.",
          "source": "https://vreeman.ai/commerce"
        },
        {
          "date": "2026-10-16",
          "signal": "Shopify Checkout MCP and Cart MCP support the UCP buyer consent extension.",
          "source": "https://vreeman.ai/commerce"
        }
      ],
      "id": "ucp",
      "name": "Universal Commerce Protocol (UCP)",
      "owner": "Google, co-developed with Shopify, Etsy, Wayfair, Target and Walmart (later joined by Amazon, Microsoft, Meta, Salesforce and Stripe)",
      "regions": [
        "United States (checkout live)",
        "Canada (planned)",
        "Australia (planned)",
        "United Kingdom (planned)"
      ],
      "settlement_rails": [
        "Cards (Google Wallet stored cards at launch; Google Pay checkout)",
        "AP2 for payment authorization"
      ],
      "sources": [
        {
          "label": "vreeman.ai: AI commerce protocols (UCP, ACP, AP2, x402)",
          "url": "https://vreeman.ai/commerce"
        },
        {
          "label": "BigCommerce UK: Agentic Checkout Explained",
          "url": "https://www.bigcommerce.co.uk/articles/ecommerce/agentic-checkout/"
        },
        {
          "label": "40rty.ai: Universal Commerce Protocol (Shopify guide)",
          "url": "https://40rty.ai/blog/universal-commerce-protocol"
        },
        {
          "label": "FourWeekMBA: Google Launches Universal Cart",
          "url": "https://fourweekmba.com/ai-google-launches-universal-cart-on-60b-listings-across-gemini/"
        },
        {
          "label": "Search Engine Land: Merchant Center UCP integration hub (US)",
          "url": "https://searchengineland.com/google-rolls-out-merchant-center-ucp-integration-hub-in-the-u-s-493889"
        }
      ],
      "versions": [
        {
          "date": "2026-01-11",
          "note": "Open standard under Apache 2.0. Five capabilities: Catalog Search and Lookup, Cart Building, Identity Linking, Checkout, Order Management. Runs over REST and JSON-RPC; compatible with MCP and A2A; works with AP2 for payments. The merchant remains merchant of record and keeps the customer relationship.",
          "version": "initial release"
        }
      ]
    },
    {
      "adoption_signals": [
        {
          "date": "2026-03-18",
          "signal": "Launch alongside Tempo mainnet; 100+ services integrated at launch (per Crossmint).",
          "source": "https://loadtest.crossmint.com/learn/agentic-payments-protocols-compared"
        },
        {
          "date": "unverified",
          "signal": "Rail extensions reported: Visa extended MPP to card payments, Stripe extended it to cards and wallets, Lightspark extended it to Bitcoin over Lightning. Dates for these extensions were not verified in sources consulted.",
          "source": "https://www.meshpay.com/blog/agentic-payment-protocols-compared"
        },
        {
          "date": "unverified",
          "signal": "Core scheme published as an IETF draft (draft-ryan-httpauth-payment-01); the proposal date was not verified in sources consulted.",
          "source": "https://testmpp.com/"
        }
      ],
      "id": "mpp",
      "name": "Machine Payments Protocol (MPP)",
      "owner": "Stripe and Tempo (Tempo: payments-focused blockchain incubated by Stripe and Paradigm)",
      "regions": [
        "Global (rail-agnostic; Tempo mainnet)"
      ],
      "settlement_rails": [
        "Tempo stablecoins",
        "Cards (Visa extension)",
        "Cards and wallets (Stripe extension)",
        "Bitcoin over Lightning (Lightspark extension)",
        "Fiat via Stripe PaymentIntents"
      ],
      "sources": [
        {
          "label": "inriver: What are AP2, MPP, and x402?",
          "url": "https://www.inriver.com/resources/ap2-mpp-x402-payment-protocols-agent-commerce/"
        },
        {
          "label": "MeshPay: Agentic Payment Protocols Compared",
          "url": "https://www.meshpay.com/blog/agentic-payment-protocols-compared"
        },
        {
          "label": "WorkOS: x402 vs Stripe MPP",
          "url": "https://workos.com/blog/x402-vs-stripe-mpp-how-to-choose-payment-infrastructure-for-ai-agents-and-mcp-tools-in-2026?utm_source=synaptic.finance&utm_medium=referral&utm_campaign=the-machine-payments-race-is-on"
        },
        {
          "label": "Crossmint: Agentic payments protocols compared",
          "url": "https://loadtest.crossmint.com/learn/agentic-payments-protocols-compared"
        },
        {
          "label": "testmpp: Test MPP agent payments",
          "url": "https://testmpp.com/"
        }
      ],
      "versions": [
        {
          "date": "2026-03-18",
          "note": "Open standard for machine-to-machine payments over HTTP, launched alongside Tempo's mainnet. Uses the HTTP 402 flow; the distinguishing primitive is the session: an agent authorizes a spending limit once, then streams many small payments without a separate on-chain transaction for each. Rail-agnostic by design; backward-compatible with x402. Unlike AP2 (FIDO) and x402 (Linux Foundation), MPP has no neutral standards body.",
          "version": "initial release"
        }
      ]
    }
  ]
}