{
  "dataset": "protocols",
  "record": {
    "id": "x402",
    "name": "x402",
    "full_name": "HTTP 402 Payments",
    "layer": "payments",
    "creator": "Coinbase + web3 ecosystem partners",
    "status": "live (165M+ transactions by Apr 2026)",
    "source": "x402 facilitator / ecosystem reporting (x402.org), 2026. Volume figures are ecosystem-reported, not independently audited.",
    "year": 2025,
    "one_liner": "Revives the dormant HTTP 402 status code so an agent can pay for a resource inline — request, get 402 with terms, pay in stablecoin, retry.",
    "spec_url": "https://x402.org",
    "snippet": "HTTP/1.1 402 Payment Required\\n{ \"accepts\": [{ \"scheme\": \"exact\", \"maxAmountRequired\": \"$0.01\", \"payTo\": \"0x...\" }] }",
    "abbreviation": "x402",
    "also_known_as": [
      "HTTP 402 Payments",
      "x402 protocol"
    ],
    "canonical_spec_url": "https://x402.org",
    "entity_uri": "https://github.com/coinbase/x402",
    "taxonomy_layer": "payments",
    "sub_layer": "inline-http-payment",
    "protocol_type": "settlement",
    "central_problem": "Lets an agent pay for a web resource inline over plain HTTP — no account, API key, or monthly invoice — by reviving the HTTP 402 status code.",
    "maintainer": "Coinbase (coinbase/x402 on GitHub) + open facilitator ecosystem",
    "governance_body": "vendor (Coinbase) + open facilitator ecosystem",
    "license": {
      "value": "Apache-2.0",
      "verify_status": "verify-against-primary-at-build",
      "source_hint": "https://github.com/coinbase/x402",
      "note": "Confirm spec/reference-impl license against the primary repo at build."
    },
    "maturity_tag": "production-ready",
    "current_spec_version": {
      "value": null,
      "verify_status": "verify-against-primary-at-build",
      "source_hint": "https://x402.org",
      "note": "x402.org does not surface an explicit spec version number; confirm against the GitHub spec at build."
    },
    "spec_date": {
      "value": null,
      "verify_status": "verify-against-primary-at-build",
      "source_hint": "https://github.com/coinbase/x402",
      "note": "Confirm current spec revision date at build."
    },
    "launch_date": {
      "value": "2025",
      "verify_status": "verify-against-primary-at-build",
      "source_hint": "https://x402.org",
      "note": "Introduced by Coinbase in 2025; confirm exact announcement date at build."
    },
    "last_verified": "2026-06-15",
    "transport": "HTTP (402 status + payment headers); on-chain stablecoin settlement (Base, Solana)",
    "core_mechanism": "A client requests a resource; the server returns HTTP 402 with accepted payment terms; the client signs a token-transfer authorization and retries with a payment header; a facilitator confirms on-chain settlement and the server delivers the resource — one extra round trip, fractions of a cent.",
    "discovery_endpoint": "HTTP 402 response with an `accepts` payment-terms array (per-resource; no fixed path)",
    "settlement_type": "stablecoin (on-chain, e.g. Base / Solana)",
    "adoption_metric": {
      "value": "165M+ transactions by ~69k agents (cumulative, by late April 2026)",
      "last_verified": null,
      "note": "Site-wide canonical x402 figure (x402 facilitator data; the live homepage uses it). NOT yet confirmed on a primary source — the cited Chainalysis page supports only ~100M+ tx through Q1 2026. Verify against the primary Coinbase/x402 source at build; do NOT ship a conflicting '50M+'.",
      "verify_status": "verify-against-primary-at-build",
      "source_hint": "https://www.coinbase.com/developer-platform/discover/launches/x402 (primary x402/Coinbase Agent.market report)"
    },
    "notable_adopters": [
      {
        "value": "Coinbase",
        "source": "https://x402.org"
      },
      {
        "value": "Cloudflare (x402 Foundation participant)",
        "source": "https://blockeden.xyz/blog/2026/03/05/x402-foundation-ai-payment-internet/"
      }
    ],
    "relationships": [
      {
        "predicate": "extends",
        "target": "ap2",
        "note": "AP2 -extends-> x402 (research §2 seed triple): AP2 builds mandate-based settlement on top of the x402 inline-payment pattern. Edge stored on both records."
      },
      {
        "predicate": "verifies",
        "target": "web-bot-auth",
        "note": "Web Bot Auth can cryptographically verify the agent making a paid x402 request."
      }
    ],
    "ideal_use_case": "Metering API or content access by the call/byte for autonomous agents, with sub-cent payments and no account setup.",
    "when_to_use": "When agents must pay tiny amounts per request inline and you want stablecoin settlement without subscriptions or API keys.",
    "when_not_to_use": "When you need card/bank rails, human-in-the-loop mandates, or larger structured purchases (use AP2 or ACP/Agentic Commerce), or when you cannot accept on-chain settlement.",
    "code_example": "HTTP/1.1 402 Payment Required\nContent-Type: application/json\n\n{ \"accepts\": [{ \"scheme\": \"exact\", \"maxAmountRequired\": \"$0.01\", \"payTo\": \"0x...\", \"network\": \"base\" }] }",
    "agent_readiness_link": "agent-readiness/x402",
    "layer_legacy": "payment"
  }
}