SYSTEM Cited by 3 sources

x402 Protocol

x402 is an open, neutral standard for Internet-native payments built on HTTP 402 Payment Required. Positioned as the "pay-per-use" primitive for the agentic web: any client (an AI agent, a browser on someone's behalf, a bot) hits an HTTP endpoint, receives 402 Payment Required with price info, pays on-demand, and is granted access.

Governance

The x402 Foundation was co-founded by Cloudflare and Coinbase — a multi-stakeholder body tasked with standardisation and neutrality. Positioned as the step up from Cloudflare's earlier proprietary pay-per-crawl headers — same 402-based shape, now under open governance instead of single-vendor control.

Request / response flow

As summarised in Cloudflare's EmDash post:

1. Client sends an HTTP request.
2. Server responds 402 Payment Required with price info.
3. Client decides to pay; sends payment (via a wallet address).
4. Server responds 200 OK with the resource.

Full header set and wallet semantics are evolving at the x402 Foundation; see the x402 spec.

Deployments

• Cloudflare pay-per-crawl — Cloudflare's 2025-07-01 launch, the first widely-deployed commercial use of HTTP 402 for paid content access. Predates the open x402 standard; Cloudflare later folded the work into x402 via the Foundation.
• EmDash — built-in x402 support on every EmDash site. "All you need to do is configure which content should require payment, set how much to charge, and provide a Wallet address." x402 embedded as a CMS primitive.
• Stripe PaymentIntents + x402 machine payments — disclosed in Stripe's 2026-03-12 agentic-commerce retrospective. Stripe's PaymentIntents API generates a per-transaction deposit address; "in an x402 flow, for example, the protocol passes the address back to the agent so it knows exactly where to remit payment." Initial settlement rail: USDC on Base; "more protocols coming." Canonical composition shape: patterns/machine-native-per-request-payment. Positions x402 as the negotiation layer feeding into Stripe's settlement backend for agent-to-API machine payments.

Role on this wiki

x402 is the standards-level realisation of the agentic paywall — the client is an agent with a budget, the server prices per-request, the negotiation happens programmatically without a human in the loop. See concepts/http-402-payment-required for the underlying HTTP primitive.

Seen in

• sources/2026-04-01-cloudflare-emdash-wordpress-spiritual-successor — x402 shipped as a built-in primitive in EmDash; every site gets per-request content monetisation out of the box.
• sources/2026-04-17-cloudflare-introducing-the-agent-readiness-score-is-your-site-agent-ready — x402 extracted from pay-per-crawl-specific headers into an industry-wide payment primitive for agents; non-scoring Agentic Commerce check layer in the Agent Readiness Score.
• sources/2026-03-12-stripe-10-things-we-learned-building-for-the-first-generation-of-agentic-commerce — Stripe's PaymentIntents API adopts x402 as the negotiation layer for agent-to-API machine payments; USDC on Base as the initial settlement rail.

Related

• concepts/http-402-payment-required — the HTTP primitive x402 builds on.
• concepts/agentic-paywall — the end-state deployment pattern x402 enables.
• concepts/machine-payment — the broader agent-to-API per-request payment concept.
• systems/pay-per-crawl — predecessor deployment (Cloudflare-specific headers).
• systems/emdash — CMS with built-in x402.
• systems/stripe-paymentintents-api — Stripe's payments API, extended to generate x402-compatible deposit addresses.
• patterns/machine-native-per-request-payment — the canonical composition of x402 + payment-provider + stablecoin.
• companies/cloudflare — x402 Foundation co-founder.
• companies/stripe — payment-provider adopter on the settlement side.