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Machine Payments Protocol (MPP)

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This page is about the Machine Payments Protocol (MPP), the open HTTP 402 payment protocol co-authored by Tempo and Stripe and launched on 2026-03-18, whose core is the "Payment" HTTP authentication scheme [1][9][16][17]. It is not x402, a separate HTTP 402 payment protocol that uses its own PAYMENT-REQUIRED, PAYMENT-SIGNATURE and PAYMENT-RESPONSE headers [4]; not L402, the Lightning Labs scheme whose 402 challenge is an L402 WWW-Authenticate header carrying a macaroon and a Lightning invoice [27]; and not the bare 402 status code, of which RFC 9110 says only: "The 402 (Payment Required) status code is reserved for future use." [28]. In the Lightning Network, "MPP" also refers to multi-part payments (the basic_mpp feature bit: "Node can receive basic multi-part payments") [29], and .mpp is the file extension of Microsoft Project files [30]. AWS writes "Machine Payment Protocol" (singular) [19]; the name used by mpp.dev, Stripe and Tempo is "Machine Payments Protocol" [1][16][17].

Overview

MPP lets a client, such as an AI agent, pay for an API call or other web resource inside the same HTTP exchange: the server answers 402 Payment Required with a payment challenge, the client pays by the method offered and retries with a credential, and the server returns the resource with a receipt [1][15]. It was launched by Tempo and Stripe on 2026-03-18, alongside Tempo's mainnet, and its core is written up as the "Payment" HTTP authentication scheme, an individual Internet-Draft that the IETF has not adopted [8][16][17]. The core does not fix a payment rail: separate method specifications cover Tempo stablecoins, cards through Stripe or Visa, Lightning and others, and each is maintained by the party behind that rail [2][6][18]. Unlike x402, it reuses the standard WWW-Authenticate and Authorization headers and can offer several methods on one endpoint, and its SDK can also serve x402 clients from the same route [4].

Who uses it

Settlers, processors, server-side proxies, and sellers that answer with WWW-Authenticate: Payment challenges.

Who reads it

Agent-side clients, SDKs and wallets that read MPP challenges and pay them.

No dated statement from Mastercard, Google, OpenAI, Anthropic, Coinbase or Shopify saying their products accept or pay over MPP was found (checked 2026-10-29). mpp.dev names Mastercard only as an example of a rail that could maintain a payment method [2].

Recent coverage

See also

References

  1. MPP, What is MPP? Machine-to-machine HTTP 402 payments (mpp.dev, Markdown version), checked 2026-10-29: "The Machine Payments Protocol (MPP) is an open protocol co-authored by Tempo and Stripe." "It lets any client—agents, apps, or humans—pay for any service in the same HTTP request." "When a client requests a paid resource, the server returns a 402 response with the payment options they support. The client chooses a payment method, fulfills the request and retries with a payment Credential which contains proof of payment. The server verifies the payment and returns the resource with a Receipt which contains proof of delivery." "MPP comes with a suite of official SDKs maintained by Tempo Labs and Wevm." — https://mpp.dev/overview.md
  2. MPP, Governance (mpp.dev, Markdown version), checked 2026-10-29: "MPP is neutral by design and operates independently of any single company, payment method, or rail." "The core specification is published as the Payment HTTP Authentication Scheme and submitted to the IETF standards track, where it continues to progress as an open, vendor-neutral standard." "Each payment method specification is defined and maintained by the rail behind it—for example Visa, Mastercard, Solana, Bitcoin, Stripe, or Tempo—together with any corporate entities associated with that rail." "Payment rails and third parties do not need explicit approval to add a payment method implementation to MPP." "MPP is developed in the open on GitHub." — https://mpp.dev/governance.md
  3. MPP, Frequently asked questions (mpp.dev, Markdown version), checked 2026-10-29: "Today, Tempo stablecoin payments, card payments through Card or Stripe, and Lightning payments are in production." "x402 only supports blockchains." "The protocol itself is free and open. There are no licensing fees for implementing MPP." — https://mpp.dev/faq.md
  4. MPP, MPP vs x402 (mpp.dev, Markdown version), checked 2026-10-29: "MPP and x402 both use HTTP 402 Payment Required to charge for API requests. x402 focuses on on-chain payment mechanisms. MPP defines a payment-method-agnostic HTTP authentication framework for stablecoins, cards, Lightning, and other payment rails." "The most important distinction is scope. x402 registers payment schemes for blockchain networks. MPP standardizes how any payment method negotiates a payment through HTTP authentication." "Challenge header PAYMENT-REQUIRED WWW-Authenticate: Payment Credential header PAYMENT-SIGNATURE Authorization: Payment, or an advertised alternate field Receipt header PAYMENT-RESPONSE Payment-Receipt" "MPP is compatible with existing x402-style charge flows." "you can run x402-compatible EVM charges inline with an MPP route: the server emits both MPP and x402 Challenges, accepts either Credential format, and returns the matching Receipt header." — https://mpp.dev/mpp-vs-x402.md
  5. MPP, HTTP 402 (mpp.dev protocol docs, Markdown version), checked 2026-10-29: "MPP uses 402 when a server offers a payment Challenge, including retryable Credential validation failures. This differs from other HTTP authentication schemes that use 401 for failed Credentials." — https://mpp.dev/protocol/http-402.md
  6. MPP, Payment methods (mpp.dev, Markdown version), checked 2026-10-29: "Payment methods define how clients pay for resources protected by the Machine Payments Protocol. Each method specifies its payment rails, Credential format, and verification logic." — https://mpp.dev/payment-methods.md
  7. MPP, Intents (mpp.dev, Markdown version), checked 2026-10-29: "For example, Tempo supports charge, session, and subscription, while Stripe currently supports charge." — https://mpp.dev/intents.md
  8. IETF Datatracker, draft-httpauth-payment, The "Payment" HTTP Authentication Scheme, checked 2026-10-29: "Document Type Active Internet-Draft (individual)" "Last updated 2026-09-09" "IESG state I-D Exists" "This I-D is not endorsed by the IETF and has no formal standing in the IETF standards process." — https://datatracker.ietf.org/doc/draft-httpauth-payment/
  9. B. Ryan, J. Moxey, T. Meagher, J. Weinstein and S. Kaliski, The "Payment" HTTP Authentication Scheme, draft-httpauth-payment-01 (IETF Datatracker HTML), 2026-09-09, checked 2026-10-29: "Internet-Draft: draft-httpauth-payment-01 Published: 9 September 2026 Intended Status: Standards Track Expires: 13 March 2027" "Authors: B. Ryan Tempo Labs J. Moxey Tempo Labs T. Meagher Tempo Labs J. Weinstein Stripe S. Kaliski Stripe" "This document defines the "Payment" HTTP authentication scheme, enabling HTTP resources to require a payment challenge to be fulfilled before access. The scheme extends HTTP Authentication, using the HTTP 402 "Payment Required" status code." "The protocol is payment-method agnostic, supporting any payment network or currency through registered payment method identifiers. Specific payment methods are defined in separate payment method specifications." — https://datatracker.ietf.org/doc/html/draft-httpauth-payment-01
  10. IETF Datatracker, draft-httpauth-payment-00, checked 2026-10-29: "Last updated 2026-06-19" — https://datatracker.ietf.org/doc/draft-httpauth-payment/00/
  11. IETF Datatracker, draft-ryan-httpauth-payment-00 (HTML), 2026-02-15, checked 2026-10-29: "Internet-Draft: draft-ryan-httpauth-payment-00 Published: 15 February 2026 Intended Status: Experimental" — https://datatracker.ietf.org/doc/html/draft-ryan-httpauth-payment-00
  12. IETF Datatracker, draft-ryan-httpauth-payment-01 (HTML), checked 2026-10-29: "Internet-Draft: draft-ryan-httpauth-payment-01 Published: 18 March 2026 Intended Status: Standards Track" — https://datatracker.ietf.org/doc/html/draft-ryan-httpauth-payment-01
  13. IETF Datatracker, draft-ryan-httpauth-payment, checked 2026-10-29: "Document Type Expired Internet-Draft (individual)" "Last updated 2026-09-18 (Latest revision 2026-03-17)" — https://datatracker.ietf.org/doc/draft-ryan-httpauth-payment/
  14. paymentauth.org, editor's rendering of draft-httpauth-payment-01, checked 2026-10-29: "Internet-Draft: draft-httpauth-payment-01 Published: 26 October 2026" — https://paymentauth.org/draft-httpauth-payment-01.html
  15. tempoxyz/mpp-specs, README.md (GitHub), checked 2026-10-29: "MPP lets any client pay as part of the HTTP exchange using the native 402 Payment Required status code." "retries the request with an Authorization: Payment credential proving payment" — https://raw.githubusercontent.com/tempoxyz/mpp-specs/main/README.md
  16. Jeff Weinstein and Steve Kaliski, Stripe Blog, Introducing the Machine Payments Protocol, 2026-03-18, checked 2026-10-29: "Introducing the Machine Payments Protocol March 18, 2026 Jeff Weinstein Product Lead, Agentic Commerce Steve Kaliski" "we're launching the Machine Payments Protocol (MPP), an open standard, internet-native way for agents to pay—co-authored by Tempo and Stripe." "Businesses can then accept payments directly from agents, in stablecoins as well as fiat with cards and buy now, pay later payment methods via Shared Payment Tokens (SPTs)." "MPP is already powering new agentic business models on Stripe. Browserbase, a browser infrastructure provider, now lets agents spin up headless browsers and pay per session." "PostalForm helps agents pay to print and send physical mail." "payment support for both MPP and x402." — https://stripe.com/blog/machine-payments-protocol
  17. Tempo, Tempo Mainnet Is Live: Build on Tempo Today, 2026-03-18, checked 2026-10-29: "Tempo Mainnet is live Mar 18, 2026" "Alongside mainnet, we're also introducing the Machine Payments Protocol (MPP), an open standard for machine payments co-authored by Stripe and Tempo." "MPP runs on Tempo today, but the protocol itself is designed to be rail-agnostic and extensible." "For example, our design partner Visa has already extended MPP to support card-based payments on their network. Stripe has extended it to support cards, wallets, and other payment methods through their platform. Lightspark has also extended it for Bitcoin payments over the Lightning network." — https://tempo.xyz/blog/mainnet/
  18. Visa, Visa introduces card specification and SDK for Machine Payments Protocol, 2026-03-18, checked 2026-10-29: "Visa introduces card specification and SDK for Machine Payments Protocol In support of Stripe and Tempo's Machine Payments Protocol, Visa enables card-based payments for trusted autonomous agent payments 03/18/2026" "Visa is extending MPP to support card-based payments on its global network, and enabling it on the Visa Acceptance Platform." "Card-Based MPP Spec: Visa's full technical specification that defines how tokenized card credentials are passed, authenticated and processed inside MPP-compatible workflows." — https://corporate.visa.com/en/sites/visa-perspectives/innovation/visa-card-specification-sdk-for-machine-payments-protocol.html
  19. Chethan Shriyan and Madhu Samhitha Vangara, AWS, Amazon Bedrock AgentCore payments is now generally available: Enabling agents to transact safely and autonomously at scale (AWS Machine Learning Blog), 2026-08-18, checked 2026-10-29: "Madhu Samhitha Vangara on 18 AUG 2026" "At GA, we have expanded protocol support to include the Machine Payment Protocol (MPP), another standard for machine payments co-authored by Stripe and Tempo, enabling developers to pay for any MPP-compatible service without an additional line of code." — https://aws.amazon.com/blogs/machine-learning/amazon-bedrock-agentcore-payments-is-now-generally-available-enabling-agents-to-transact-safely-and-autonomously-at-scale/
  20. Cloudflare, MPP (Machine Payments Protocol), Cloudflare Agents docs (Markdown version), last updated 2026-08-05, checked 2026-10-29: "Last updated Aug 5, 2026" "MPP is payment-method agnostic. It supports stablecoins, cards through Stripe, and custom payment methods. A service can offer more than one method." "MPP clients can consume existing x402 services without changes to those services." — https://developers.cloudflare.com/agents/tools/payments/mpp/index.md
  21. Lightning Labs, Aperture | Builder's Guide, checked 2026-10-29: "Aperture is a reverse proxy that acts as a payment and authentication gateway for Lightning Network powered APIs." "Aperture implements both the L402 as well as the MPP specifications." — https://docs.lightning.engineering/lightning-network-tools/aperture
  22. Stripe Documentation, MPP (docs.stripe.com), checked 2026-10-29: "MPP, the Machine Payments Protocol, is an open protocol that lets agents pay for your APIs and services programmatically without a checkout UI, co-authored by Stripe and Tempo." "When an agent requests your API or service, your server returns an HTTP 402 response with payment details. The agent authorizes the payment, retries the request, and gets access to the paid resource along with a receipt." "Use MPP to accept payments from agents with a variety of payment methods, including cards through Shared Payment Tokens (SPTs) and stablecoin payments." "Stripe automatically offramps these payments and settles them into your Stripe balance." "Agents with stablecoins send payments to this onchain address on supported blockchains, such as Tempo." "The link-cli is a tool that can provision one-time shared payment token credentials using your Link account. Follow the instructions at link.com/agents to install the link-cli skills or register it as an MCP server in your preferred agent." "In a sandbox, the CLI automatically completes roundtrip test transactions against your server. In live mode, the CLI can also complete roundtrip transactions with real funds." — https://docs.stripe.com/payments/machine/mpp
  23. MPP, service directory catalog (JSON, mpp.dev/api/services; fields read: id, integration, methods), checked 2026-10-29: "browserbase" "postalform" "alchemy" "apify" "pinata" — https://mpp.dev/api/services
  24. Ben Weiss, Fortune, Stripe-backed crypto startup Tempo releases AI payments protocol, launches blockchain, 2026-03-18, checked 2026-10-29: "March 18, 2026, 9:00 AM ET" "Dubbed the "Machine Payments Protocol," the open-source network supports payments in both fiat and cryptocurrency." ""We look at MPP as another way that you can have a very clear, defined protocol around how an agent communicates with merchants," Cuy Sheffield, Visa's head of crypto, told Fortune." — https://fortune.com/2026/03/18/stripe-tempo-paradigm-mpp-ai-payments-protocol/
  25. PYMNTS, Visa Teams With Stripe on Agent Payments, 2026-03-18, checked 2026-10-29: "Visa Teams With Stripe on Agent Payments By PYMNTS | March 18, 2026" "The company is extending MPP to support card-based payments on its global network and enabling the protocol on the Visa Acceptance Platform, it said in a Wednesday (March 18) press release." — https://www.pymnts.com/news/payment-methods/2026/visa-scales-agentic-commerce-through-stripe-protocol-collaboration/
  26. Adewale Amure, FinanceTracked, AI agent payments have rails and almost no traffic, 2026-09-18, checked 2026-10-29: "Written by Adewale Amure Edited by Omobolade Ajibade Sep 18, 2026" "Google, Visa, Mastercard, Stripe, OpenAI, Coinbase and Ant International have all shipped a protocol that lets AI agents pay for things, from a grocery order or a flight booking to a single API call." "Its Machine Payments Protocol sits alongside that as the standard through which AI agents transact with businesses." — https://financetracked.com/ai-agent-payments
  27. Lightning Labs, Protocol Specification | Builder's Guide (L402), checked 2026-10-29: "WWW-Authenticate: L402 macaroon=" — https://docs.lightning.engineering/the-lightning-network/l402/protocol-specification
  28. IETF, RFC 9110: HTTP Semantics, section 15.5.3, checked 2026-10-29: "The 402 (Payment Required) status code is reserved for future use." — https://www.rfc-editor.org/rfc/rfc9110.html
  29. Lightning Network specifications, BOLT #9, 09-features.md (GitHub), checked 2026-10-29: "Node can receive basic multi-part payments" — https://raw.githubusercontent.com/lightning/bolts/master/09-features.md
  30. Microsoft Learn, Import projects from the Microsoft Project desktop client, checked 2026-10-29: "Microsoft Dynamics 365 Project Operations lets project managers import their Microsoft Project desktop client files (.mpp files) to create projects." — https://learn.microsoft.com/en-us/dynamics365/project-operations/project-management/import_from_mpp
  31. Stripe, Link CLI (stripe/link-cli on GitHub), checked 2026-10-29: "Install the skills: npx skills add stripe/link-cli" "A Shared Payment Token (SPT) for use when the seller accepts programmatic payments through Machine Payment Protocols (MPP) For now, this is only available to US and Canadian Link accounts." "Use mpp pay to complete purchases" — https://github.com/stripe/link-cli
  32. MPP, SDKs (mpp.dev, Markdown version), checked 2026-10-29: "the reference implementation of the MPP SDKs" — https://mpp.dev/sdk.md
  33. Cloudflare Agents docs, Pay from the Agents SDK (Markdown version), last updated 2026-08-05, checked 2026-10-29: "Last updated Aug 5, 2026" "Configure a Cloudflare Agent to pay HTTP services and Model Context Protocol (MCP) tools with Machine Payments Protocol (MPP)." — https://developers.cloudflare.com/agents/tools/payments/mpp/pay-from-agents-sdk/index.md
  34. MPP, MPP services: APIs that accept MPP payments (mpp.dev/services), checked 2026-10-29: "The curated directory accepts live, production-ready MPP services." "Install the Tempo CLI and its wallet to fund your agent's use of MPP services." — https://mpp.dev/services
  35. Tempo, Website for the Machine Payments Protocol (tempoxyz/mpp on GitHub), checked 2026-10-29: "The service directory at mpp.dev/services is curated for live, production-ready MPP services." "Register on MPPScan for immediate discovery; open a PR to include it in the curated mpp.dev/services list" — https://github.com/tempoxyz/mpp

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