# x402 Explained: HTTP 402 for Machine-Native Payments A neutral guide to x402: Coinbase's open protocol that revives the HTTP 402 status so software can pay software in stablecoins, how the facilitator model works, who governs it, and how it relates to MPP and AP2. URL: https://agenticcommerceatlas.com/learn/x402-explained/ Author: Andrew McPherson | Publisher: Agentic Commerce Atlas Updated: 2026-10-31 --- x402 is Coinbase's open protocol that revives the long-dormant HTTP **402 "Payment Required"** status so that software can pay for resources programmatically, typically with stablecoins, in amounts and at frequencies that card rails handle poorly. It is not a consumer-checkout protocol. It sits at the **settlement** layer and exists for software paying software: an agent paying for an API call, compute, data, or content. ## How payment flows The mechanism is the elegant part. A client requests a resource from a service; the service responds with a **402** and a payment requirement; the client pays; and a **facilitator** verifies and settles the payment **on-chain** on the merchant's behalf before the resource is delivered. The facilitator model is what makes x402 practical: the merchant does not have to run blockchain infrastructure itself, it relies on the facilitator to verify and settle. Settlement is in stablecoins such as USDC, which suits micro-transactions and per-call billing where traditional rails are too slow or too expensive. ## Who is behind it x402 comes from **Coinbase**, and is crypto-native by design. Coinbase and **Cloudflare** announced their intent to form an **x402 Foundation** in September 2025 to steward the protocol, and it moved under the **Linux Foundation** in 2026, giving it neutral, multi-party governance. That early move to a foundation is a familiar pattern: the crypto-native standard leans on neutral stewardship sooner, while provider-backed standards often start under their sponsors. In mid-2026 the protocol gained meaningful infrastructure backing. **AWS** shipped x402 enforcement at the edge as an AI traffic monetization capability of AWS WAF Bot Control, available at no additional charge wherever a Web ACL is attached to a CloudFront distribution (AWS does not itself use the words "generally available"), and **Cloudflare** opened a waitlist (moved to closed beta on 30 September 2026) for a **Monetization Gateway** that lets sites charge for pages, APIs, datasets, or MCP tools via x402, both settling in stablecoins (primarily USDC) through Coinbase's facilitator. Then, on **July 14, 2026**, the **Linux Foundation** announced the **operational launch** of the x402 Foundation under formal, open governance, with Coinbase's contribution of the protocol complete and **40 members** on board at launch. The premier tier is striking for a crypto-native rail: its seventeen members span the major card networks and payment providers (**Visa, Mastercard, American Express, Stripe, Adyen, Fiserv**), platforms (**Google, Shopify, AWS, Cloudflare**), and crypto infrastructure (**Coinbase, Circle, Ripple, MoonPay**, and the Monad, Solana and Stellar foundations). Membership has grown past that launch figure: the foundation's members page now lists 57 organizations: 19 premier (the premier tier now also includes PayPal and Sui), 26 general, and 12 associate. On **24 September 2026** **Block** announced it had joined the foundation and contributed **Bitcoin Lightning** payments to the protocol, the first major non-stablecoin rail in x402. On 20 October 2026 **Mastercard** made early-access buyer- and seller-side APIs available for Agent Pay for Machines, which it describes as building on x402 and connecting it to the Mastercard network. Two hyperscalers enforcing the same payment protocol at the edge, and every major card network signing on to help govern it, is a signal that agent-to-service micropayments are moving from concept to infrastructure, though open questions remain around tax, invoicing, and how sellers distinguish paying agents from ordinary traffic. The handover is now visible in the code as well as the governance. The canonical repository is **`github.com/x402-foundation/x402`**; Coinbase's original `coinbase/x402` repository was moved under the Foundation, with issues and pull requests transferred, and now serves as a development fork. The published documentation moved with it, to **docs.x402.org**. Worth noting alongside the stablecoin framing: the project's own principles describe x402 as **network, token, and currency agnostic**, and the Linux Foundation describes it as supporting "payment types ranging from traditional cards to stablecoins." Stablecoins are current practice, not a limit written into the specification. ## Where it sits in the stack x402 is one of two machine-native settlement standards, alongside [MPP](/learn/mpp-explained/). Both build on HTTP 402 and target the same agent-to-agent and micro-transaction use cases; the difference is sponsorship and rails, and Stripe supports both. For a side-by-side, see [x402 vs MPP](/learn/x402-vs-mpp/). It also connects to the authorization layer. An **A2A x402 extension**, built by Google with Coinbase, the Ethereum Foundation, and MetaMask, brings x402-style stablecoin payments to the [A2A](/learn/a2a-explained/) agent-to-agent protocol, which is how [AP2](/learn/ap2-explained/) composes with crypto settlement. So x402 handles the money movement, while AP2 and A2A handle authorization and coordination around it. For the full map, see [the protocol stack](/learn/agentic-commerce-protocol-stack/). ## Frequently asked questions ### What is x402? x402 is Coinbase's open protocol that revives the long-dormant HTTP 402 'Payment Required' status so software can pay for resources programmatically, typically in stablecoins. It sits at the settlement layer and targets machine-to-machine and micro-transaction use cases rather than consumer retail checkout. ### How does payment work in x402? A client requests a resource; the server responds with a 402 and a payment requirement; the client pays; and a facilitator verifies and settles the payment on-chain on the merchant's behalf before the resource is delivered. The facilitator model means the merchant does not have to operate blockchain infrastructure directly. ### How is x402 different from MPP? Both are machine-native settlement standards built on HTTP 402. x402 is Coinbase's stablecoin-focused protocol settling on-chain through a facilitator; MPP is Stripe and Tempo's, settling in stablecoins as well as the cards, wallets, and other methods Shared Payment Tokens carry. Stripe supports both. See the x402 vs MPP comparison for a side-by-side. ## Primary sources - What happens when AI agents start paying each other? Watch Mastercard Agent Pay for Machines in action: https://www.mastercard.com/us/en/news-and-trends/press/2026/october/Mastercard-Agent-Pay-for-Machines-in-action.html - Monetization Gateway closed beta: https://developers.cloudflare.com/changelog/post/2026-09-30-closed-beta/ - x402 protocol (GitHub): https://github.com/x402-foundation/x402 - x402 documentation: https://docs.x402.org/introduction - A2A x402 extension (GitHub): https://github.com/google-agentic-commerce/a2a-x402 - Coinbase and AWS let publishers accept agents as customers via x402: https://www.coinbase.com/blog/coinbase-and-aws-let-publishers-accept-agents-as-customers-via-x402 - Cloudflare Monetization Gateway: https://blog.cloudflare.com/monetization-gateway/ - Linux Foundation announces operational launch of x402 Foundation: https://www.linuxfoundation.org/press/linux-foundation-announces-operational-launch-of-x402-foundation-to-standardize-internet-native-payments-for-ai-agents-and-applications - Block joins the x402 Foundation to advance open agentic commerce: https://block.xyz/inside/block-joins-the-x402-foundation-to-advance-open-agentic-commerce - x402 Foundation members: https://x402.org/members/