Updated 2026-10-18

What is x402? The pay-per-call standard for AI agents

x402 is an open payment standard built on the HTTP 402 Payment Required status code. A server answers a request with payment details; the client, often an AI agent, signs a payment and retries; the server verifies, settles and returns the resource. The x402 Foundation at the Linux Foundation now provides its neutral, openly governed home.

What is x402, in one paragraph?

x402 is an open payment standard that uses HTTP's 402 Payment Required status so a client can pay for a resource inside a normal web request. The docs call it a completely open standard under the Apache-2.0 license, with no fees built into the standard. (x402 docs)

How does x402 work, step by step?

  1. The client requests a resource.
  2. The server replies 402 with a PAYMENT-REQUIRED header describing what it accepts.
  3. The client retries with a signed payment in PAYMENT-SIGNATURE.
  4. The server (often through a facilitator) verifies and settles the payment, then returns the resource with PAYMENT-RESPONSE.

Source: HTTP 402 in x402, Facilitator.

Why is x402 rising now?

What is x402 used for?

Per x402.org: API monetization, agentic commerce and paywalled content. The x402 v2 specification also describes carrying payments over MCP and A2A, not only plain HTTP. (spec)

How do you start with x402 as a buyer or seller?

Buyers (agents): a dedicated wallet, a strict spend cap, and a shortlist of endpoints with good scores from the x402 API list. Sellers: add the x402 middleware to the route you want to charge for, pick a facilitator, and test with small prices first. (seller quickstart)

What do third-party x402 adoption numbers show, and what are the caveats?

x402.org shows a live 30-day counter of transactions and volume on its home page. These are self-reported figures and change daily; we don't repeat third-party dashboards we can't verify. Our own figure is the endpoint count above.

Which tools support this trend?

ScoreToolTypeHost
100api-xpay.com payment
Payment receipt with transaction details
x402 · $0.005www.api-xpay.com
100api.onesource.io erc20-balance
ERC20 token balance for any Ethereum wallet - USDC, USDT, DAI, or any token - via balanceOf (eth_call) on OneS
x402 · $0.003api.onesource.io
100x402.botsmith.dev search
X Tweet Search ($0.02/call): Search X (Twitter) posts with full advanced-search syntax (from:, since:, until:,
x402 · $0.02x402.botsmith.dev
100cheaptokens.ai buy
OpenAI-compatible LLM inference and chat completions via discounted Venice API credits. Pay USDC to receive a
x402 · $1cheaptokens.ai
100api.onesource.io live-balance
Live wallet balance - native ETH plus up to 20 caller-supplied ERC20 tokens in one bounded RPC batch
x402 · $0.003api.onesource.io
100api.402rates.com ping
Payment integration check for 0.001 USDC; no external data lookup. Returns time, rail, network mode and free/p
x402 · $0.001api.402rates.com
100api.oblique.markets time
Use when an agent needs a trusted UTC timestamp or the smallest end-to-end test of its x402 payment client. Re
x402 · $0.01api.oblique.markets
100wallets-demo-seller-server.calebgcarithers.workers.dev weather
Real-time current weather conditions for a city or location, including temperature, humidity, precipitation, w
x402 · $0.001wallets-demo-seller-server.calebgcarithers.workers.dev
100api.chit402.com completions
Signed spend receipts for agent x402 payments — who paid which call, verifiable by a third party. Treasury des
x402 · $0.002api.chit402.com
100api.oblique.markets bazaar-pulse
Use when an agent wants one-call situational awareness of the x402 Bazaar before choosing what to buy or sell.
x402 · $0.002api.oblique.markets
100api.bitrefill.com detail
Get a product's packages, pricing, and recipient requirements before creating an invoice.
x402 · $0.001api.bitrefill.com
100rpc.nodeflare.app x402
Base RPC (chain 8453): JSON-RPC over HTTPS on NodeFlare's own bare-metal nodes. Pay per request in USDC, no ac
x402 · $0.001rpc.nodeflare.app
100x402.aispace.bot generate
Text-to-image generation on Venice models (Flux, SD3.5, GPT-Image, HunyuanImage, and more), paid per request i
x402 · $0.015x402.aispace.bot
100gas.apitoll.cloud gas
Base gas oracle / gas price API for AI agents and bots — get the gas price for a transaction on Base in one x4
x402 · $0.001gas.apitoll.cloud
100api.nansen.ai related-wallets
Get Address Related Wallets Data
x402 · $0.01api.nansen.ai
100x402uselessfacts.vercel.app useless-fact
Pay a tiny amount of USDC and receive one delightfully useless fact.
x402 · $0.001x402uselessfacts.vercel.app
100ladyfortunalx402.vercel.app fortune
Get a random fortune via x402 payment on Base mainnet.
x402 · $0.01ladyfortunalx402.vercel.app
100api.loyalspark.online rewards
Onchain loyalty platform on Base Network. Businesses launch branded rewards in minutes, customers earn real va
x402 · $0.001api.loyalspark.online
100api.loyalspark.online reward-status
Onchain loyalty platform on Base Network. Businesses launch branded rewards in minutes, customers earn real va
x402 · $0.001api.loyalspark.online
100x402.sniperx.fun smarttraders_smartmoney
Get SmartMoney trading activities on token (sorted by time descending)
x402 · $0.02x402.sniperx.fun

See also: agent marketplaces & task boards that pay agents over x402 and on-chain.

What else do people ask?

What is x402?

x402 is an open standard for internet-native payments that uses the HTTP 402 Payment Required status code. It lets clients, including AI agents, pay for APIs and content per request without accounts, sessions or API keys.

Who created x402 and who runs it now?

The x402 Foundation at the Linux Foundation governs it; the foundation launched operationally in July 2026, and on Oct 1, 2026 the Linux Foundation appointed Michael Hursta as executive director, leading 50+ member organizations. Block's Sept 24, 2026 announcement quotes Erik Reppel as the creator of x402.

What is x402 used for?

Its main uses are APIs paid per request, AI agents paying for API access themselves, paywalls for digital content and micropayment-priced tools. The specification also describes x402 payments across MCP tools and agent-to-agent (A2A) calls.

What is an x402 facilitator?

A facilitator is an optional service that verifies a client's payment payload and settles it onchain for the server, so the server doesn't need its own blockchain infrastructure. Cloudflare's docs note a public facilitator at x402.org/facilitator, operated by Coinbase.

Does x402 charge fees?

The x402 standard has no fees built in. Networks, facilitators or sellers may still have their own costs, so check the endpoint before calling it.

How big is x402 adoption?

Figures vary by source, so treat third-party and self-reported numbers with caution. x402.org shows a live 30-day transaction counter on its home page, and our own crawl currently lists 607 x402 endpoints.

Is x402 only for crypto?

Today x402 payments are crypto-native, typically stablecoins such as USDC, and the docs describe crypto payments as the core. On Sept 24, 2026 Block announced it had joined the x402 Foundation and contributed Bitcoin Lightning payments to the protocol.

What should you read next on DartzDabz?

Sources

  1. docs.x402.org/introduction
  2. docs.x402.org/core-concepts/http-402
  3. docs.x402.org/core-concepts/facilitator
  4. github.com/x402-foundation/x402/blob/main/specs/x402-specification-v2.md
  5. developers.cloudflare.com/agents/tools/payments/x402/
  6. www.linuxfoundation.org/press/linux-foundation-appoints-michael-hursta-as-executive-director-of-the-x402-foundation
  7. block.xyz/inside/block-joins-the-x402-foundation-to-advance-open-agentic-commerce
  8. www.x402.org

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