Frequently asked questions

x402 is an open payment protocol introduced by Coinbase in 2025 that turns the HTTP 402 Payment Required status code into a machine-to-machine payment standard. It lets autonomous AI agents pay for HTTP services with onchain stablecoins (USDC on Base) without per-call human approval. When a service replies with HTTP 402, the agent reads the payment requirements from the response headers, signs an EIP-3009 authorization for the requested amount, and hands the signature to a facilitator. The facilitator broadcasts it on-chain, USDC moves from agent to merchant, and the service then returns the actual content. The protocol is open: Coinbase publishes the reference implementation at github.com/coinbase/x402, but no single entity controls it. Anyone can run a facilitator, anyone can sign authorizations, and any chain with EIP-3009-capable USDC can host x402 traffic. As of May 2026, about 89% of observed x402 volume settles on Base mainnet.

An AI agent pays via x402 in four steps. First, the agent calls an HTTP endpoint; the server replies with status 402 and a JSON header listing the price, the merchant wallet, the chain, and a payment nonce. Second, the agent signs an EIP-3009 authorization off-chain — a structured EIP-712 typed-data signature that commits to transferring N USDC from the agent wallet to the merchant wallet, valid until a specific timestamp. Third, the agent submits the signature to a facilitator service (Coinbase Developer Platform, OpenFacilitator, Primer), which broadcasts the authorization on-chain inside a single Base transaction and pays the gas cost itself. Fourth, the USDC contract verifies the signature, executes the transfer, and emits the AuthorizationUsed event. The original HTTP request is then replayed with proof of payment, and the service returns the actual content.

No. x402 is a protocol — a way to invoke and settle a payment over HTTP. USDC is the asset being moved. On Base, 100% of observed x402 volume settles in USDC because USDC implements EIP-3009, which is what makes the signed-authorization flow possible. In principle x402 could settle in any EIP-3009-compatible token.

x402 is an open specification published by Coinbase. The reference implementation is open-source (github.com/coinbase/x402). No single entity controls it on-chain — anyone can run a facilitator, anyone can sign authorizations, and the underlying primitives (EIP-3009 on USDC) are part of the ERC-20 extension family. Coinbase is the de facto standard-setter but the protocol is not gated by them.

As of 2026-04, virtually all observed x402 volume is on Base mainnet (chain id 8453). The protocol is theoretically chain-agnostic — any chain with a USDC deployment that supports EIP-3009 can host x402 traffic. Coinbase's reference facilitator is Base-first.

Because the agent never broadcasts its own transaction. In x402, the agent only signs an EIP-3009 authorization off-chain — a typed-data signature that commits to a specific USDC transfer. The agent then hands that signature to a facilitator (Coinbase Developer Platform, OpenFacilitator, Primer), and the facilitator broadcasts it on-chain inside a single Base transaction. The facilitator wallet pays gas and shows up as tx.from in any block explorer. The real payer — the EIP-3009 authorizer, also known as the agent — sits in topics[1] of the AuthorizationUsed event emitted by the USDC contract. Naive explorers that read tx.from will rank the facilitator at the top of every leaderboard and miss the actual agent entirely. lookx402 always decodes from topics[1], which is why our top-agent list differs from what you would see on Etherscan or Basescan when sorting by tx.from.

x402scan focuses on raw transaction tables — useful for developers who want to inspect individual tx hashes. lookx402 aggregates the same on-chain data into per-agent profiles, behavioral archetypes (sprinter, marathoner, ghost, etc.), dyads (payer-merchant relationship graphs), and narrative views — useful for journalists, researchers, and businesses tracking the agentic economy. We also de-confuse the facilitator-vs-agent attribution that naive explorers get wrong. See /vs/x402scan for a full side-by-side.

Etherscan is a general-purpose explorer — it shows every transaction on a chain but does not group them by economic actor and does not understand the x402 facilitator-vs-agent distinction. lookx402 is purpose-built for the x402 protocol: it decodes the EIP-3009 authorizer correctly, aggregates by agent/merchant/dyad, classifies behavior, and surfaces the relationship graph that matters for the agentic economy. See /vs/etherscan.

Yes — if you know the agent's wallet address. Visit https://lookx402.com/agent/<0xaddress> for a full profile including every x402 transaction, total volume in USDC, distinct merchants paid, lifetime in days, behavioral archetype, and dyads (merchants this agent recurs with). Profiles are server-rendered, indexed by Google, and have JSON-LD for AI citation.

We never rely on tx.from. We index the USDC AuthorizationUsed event signature directly — its topics[1] is the EIP-3009 authorizer (the agent). We then match it to the paired Transfer event by transaction hash to get the merchant. The facilitator's wallet is treated as a transparent relay and is excluded from leaderboards. See methodology for the full decoding logic.

A dyad is a (payer, merchant) pair that we have observed transacting at least once. Dyads with high tx count or volume represent persistent relationships — a specific agent repeatedly paying a specific service. The /api/dyads endpoint returns the top such pairs by volume or transaction count.

Because x402 was designed for permissionless service monetization. Any service operator can spin up a wallet, accept x402 payments, and start earning USDC without identifying themselves. Only services published in directories like PayAI or the Coinbase x402 partner list (which together cover ~1% of observed recipient wallets) currently have public labels. The other 99% are unlabeled by design.

As of May 2026, the largest single x402 transaction on Base is just under $500 000 USDC. Roughly 0.4% of transactions are above $100 USDC and these represent ~90% of total dollar volume. The median transaction is much smaller — about 0.001 USDC (one tenth of one cent) — typical of micropayment-per-API-call patterns.

As of May 2026, the top agent by lifetime USDC volume is approaching $5 million in cumulative x402 spending over ~33 days. Concentration is extreme: the top single wallet typically represents ~45% of all x402 USDC volume, and the top 10 wallets represent ~95%. See /api/agents/top for the live ranking.

USDC has 6 decimals, so the absolute floor for a non-zero x402 transaction is 0.000001 USDC (one millionth of a dollar). Most x402 micro-payments cluster around 0.001 USDC (one tenth of a cent), which is the typical per-call price for cheap LLM endpoints and search APIs.

The classifier is rule-based, not ML, so it is deterministic and reproducible. Every classification ships with a confidence score (0.0–1.0) based on how cleanly the agent matches the archetype rule. Agents with fewer than 30 transactions are typically labeled unknown rather than guessed. The hourly classifier reruns from scratch each cycle — there is no carry-over bias.

Live ingest runs every 5 minutes via a Cloudflare Worker. Behavioral classification (which assigns archetypes) runs hourly. Materialized views for top agents, top merchants, and dyads recompute after every ingest cycle. The /api/recent-tx endpoint typically reflects new transactions within 6 minutes of confirmation.

Base mainnet RPC, polled directly every 5 minutes. We rotate across four free public RPC providers (publicnode, llamarpc, drpc, meowrpc) — no paid provider is required. We do not use any indexer (no Alchemy, no QuickNode, no Goldsky, no Subsquid). Data lands in a Supabase Postgres database. The full pipeline is documented at /methodology.

It can be briefly delayed. The 5-minute ingest cycle means a newly-confirmed transaction might take up to ~6 minutes to appear in our profiles. The classifier runs hourly so an archetype label may lag the underlying activity by up to 60 minutes. We never miss transactions thanks to a 30-block safety overlap on the live indexer, and we run a separate 30-day backfill job to catch anything that slipped through during downtime.

Yes. The JSON API at /api is fully public, read-only, and unauthenticated. No key, no rate limit, no commercial restriction beyond polite use. Cache-friendly: every endpoint sets stale-while-revalidate so Cloudflare absorbs most repeat traffic. Attribution back to lookx402.com is appreciated but not required.

Not as a single bulk dump (yet). However, every transaction is queryable via the public JSON API at /api, and we expose paginated leaderboards for agents, merchants, dyads, and recent transactions. If you have a research use case that needs the full set, ping @lookx402 on X.

Yes — https://lookx402.com/feed.xml. The feed publishes notable events: new whales (single tx ≥ $100), new sprinters (≥100 tx in ≤1 day), and weekly leaderboard wraps. Subscribe in any RSS reader.

Open https://lookx402.com/agent/<0xyourwallet> with the agent's wallet address. You will get a full server-rendered profile listing every x402 transaction the agent has authorized, the total USDC volume moved, the distinct merchants paid, the behavioral archetype assigned by our hourly classifier, and the top dyads (recurring merchant relationships). Profiles are public, free, unauthenticated, and indexable by AI search engines. Each transaction row shows the block timestamp, the merchant wallet, and the USDC amount in atomic units. If the wallet has zero x402 activity yet, the page returns 404 — that means lookx402 has indexed every Base block but found no AuthorizationUsed event with this wallet in topics[1]. For raw JSON, query the same data at https://lookx402.com/api/agent/<0xyourwallet>. New transactions appear within 6 minutes of confirmation thanks to a 5-minute Cloudflare Worker cron.

For micropayments below $1, x402 is dramatically cheaper than Stripe or PayPal. Stripe charges 2.9% plus $0.30 per transaction, which makes a $0.001 API call economically impossible — the fee is 30,000% of the payment. x402 on Base costs the facilitator about $0.0001 in gas per transaction; the merchant receives close to 100% of the USDC amount. The median x402 transaction observed by lookx402 is around $0.001 — one tenth of one cent. That price point is what enables true per-call billing of LLM endpoints, search APIs, and agent compute. For larger payments above $50, the gap narrows because absolute amounts dominate. x402 is therefore best understood as a complement to legacy rails for the specific use case of automated, high-frequency, low-value machine-to-machine billing, not a wholesale replacement for human-facing commerce.

Coinbase Commerce processes regulated stablecoin payments for human-facing e-commerce — invoices, checkouts, subscriptions — and reports cumulative crypto payment volume in the high-billions of dollars across all chains. x402 is a different beast: it is purpose-built for machine-to-machine micropayments and runs almost entirely on Base. As of May 2026, lookx402 has indexed cumulative x402 volume around $80 million USDC over roughly 3.5 million transactions. The two systems target different markets and shouldn't be compared on volume alone. x402 wins decisively on transaction count, agent-pay-agent economic novelty, and per-call price floor; Coinbase Commerce wins on absolute dollar throughput, merchant onboarding tooling, and human-buyer UX. We track x402 in real time at /state-of-x402 for cumulative aggregates that anyone can cite.

Ping the project on X at @lookx402 with the wallet address, the suspicious behavior you observed, and the URL of the relevant lookx402 profile page. Examples of reportable patterns include: a wallet impersonating a known merchant (paid labelling fraud), a service draining funds without delivering, an agent producing high tx volume that looks like a denial-of-service against a merchant, or any pattern that suggests private-key compromise. We do not deanonymize wallets and we do not freeze funds — lookx402 has no custody and no kill switch. What we can do is flag the wallet in our enrichment registry, document the pattern publicly in the methodology changelog, and update any related labels. We acknowledge within 48 hours and respond within 7 days per our corrections policy. Reports stay confidential unless the reporter explicitly asks for public attribution.

Yes — every transaction is queryable via the public JSON API at https://lookx402.com/api with no key, no rate limit, and no commercial restriction. For a single agent, /api/agent/<0xwallet> returns all observed transactions, dyads, and the assigned archetype as JSON. For a merchant, /api/merchant/<0xwallet> returns received payments and distinct paying agents. For a date range, the recent-tx endpoint accepts time-window parameters and returns up to 500 transactions per request with cursor pagination. The full ranked agent and merchant leaderboards live at /api/agents/top and /api/merchants/top respectively. A bulk dataset dump is on the roadmap but not yet exposed as a single download; if you need the complete history for academic research or a regulatory inquiry, ping @lookx402 on X and we can produce a one-off Parquet export. Attribution to lookx402.com is appreciated but never required.

No. lookx402 is an independent project. We have no affiliation with Coinbase, the x402 protocol working group, any facilitator, or any merchant we index. We are a passive observer of public on-chain data.

No. We deliberately stay at the entity/wallet/auto-declared-label level only. We never attempt to identify natural persons behind wallets. Where a wallet has been publicly self-declared by a company (e.g. Anthropic publishes a wallet on its website), we may reference that public label. We do not chain-cluster wallets to real-world identities and we treat the agent economy's pseudonymity as a design property to respect, not a puzzle to solve.

Publish the wallet address on a page you control (your docs, your website, your GitHub README) with a clear statement that it is the recipient address for your x402-paid service. Then ping us on X (@lookx402) with the link and the address. We add verified self-declared labels to our enrichment registry. We do not accept paid labelling.

The standard sitemap.xml is for traditional search engines (Google, Bing). The ai-sitemap.xml is a curated subset of canonical content URLs intended for AI training and citation crawlers (GPTBot, ClaudeBot, PerplexityBot, etc.). Both are publicly accessible and both are referenced from robots.txt.

Deliberate. lookx402 is a public observatory — its job is to surface on-chain reality without theatrics. We use a single dark theme, monospace numerics, and no animations or paywalls. The page is one HTML file, no framework, no build step, no JavaScript dependency beyond a minimal Supabase client. It loads in well under a second on a cold cache.