lookx402 stats · methodology · archetypes · what is x402

What is x402?

x402 is an open payment protocol that uses the HTTP 402 "Payment Required" status code to let software, especially AI agents, pay for APIs and services programmatically. A client calls an endpoint, gets a 402 response with payment terms, pays on-chain in USDC on Base, and retries with proof of payment to unlock the resource, with no account or API key required.

How an x402 payment works

  1. The agent requests a paid resource and receives HTTP 402 Payment Required with the price and a payment address.
  2. The agent pays in USDC on Base (sub-cent fees, instant settlement).
  3. The agent retries the request with proof of payment; the service verifies it on-chain and returns the resource.

Why it matters for AI agents

Autonomous agents cannot fill in signup forms or manage API keys at scale. x402 lets an agent pay any compatible endpoint inline, per call, account-free, so machine-to-machine commerce can happen without human onboarding.

x402 on Base, by the numbers

lookx402 is a live explorer of every x402 payment on Base mainnet. As of 2026-06-01: 3 900 109 payments, 128 187 agents, 62 887 services, $96 771 310 in USDC. See the state of x402, browse agent archetypes, or read the methodology.

FAQ

What is x402?

x402 is an open payment protocol that revives the HTTP 402 "Payment Required" status code so that software, including AI agents, can pay for APIs and services programmatically. A client requests a resource, receives a 402 with payment terms, pays on-chain (USDC on Base), and retries with proof of payment to unlock the response, with no account or API key needed.

What blockchain does x402 use?

x402 payments in this dataset settle in USDC on Base, Coinbase's Ethereum L2. Base offers sub-cent fees and fast finality, which suits the many tiny machine-to-machine payments x402 is designed for.

Who uses x402?

Mostly autonomous AI agents paying for APIs, inference, and data. As of 2026-06-01, lookx402 had indexed 128 187 distinct agent wallets making 3 900 109 x402 payments to 62 887 services on Base.

How is x402 different from a normal API key?

An API key authenticates a known account billed later. x402 settles payment inline per request, on-chain and account-free, so an agent can pay any x402-enabled endpoint instantly without signing up, and the service is paid immediately.