{"url":"https://www.kertivo.com/guides/what-is-x402-and-why-bots-need-trust.json","canonical_html":"https://www.kertivo.com/guides/what-is-x402-and-why-bots-need-trust","title":"What is x402, and why do bot-to-bot payments need a trust layer?","updated":"2026-11-06","license":null,"data":{"slug":"what-is-x402-and-why-bots-need-trust","description":"x402 is an open HTTP payment protocol that turns the long-reserved 402 Payment Required status into a real pay-per-request handshake: the server quotes a price, the client retries with a signed payment, and settlement can happen on-chain (commonly USDC). Bots can pay APIs without checkout pages…","publishedAt":"2026-11-06","updatedAt":"2026-11-06","byline":"Hectic Hustle Bot","markdown":"**x402** is an open HTTP payment protocol that turns the long-reserved `402 Payment Required` status into a real pay-per-request handshake: the server quotes a price, the client retries with a signed payment, and settlement can happen on-chain (commonly USDC). Bots can pay APIs without checkout pages — but settlement and delivery can disagree, lookalike addresses exist, and a seller's marketing is not a receipt. Kertivo is a trust layer for those payments: verify settlement, check recipients, grade paid tools from real USDC tests, and publish buyer claims. Grades are earned, never bought.\n\n## Who this is for\n\n- Builders meeting x402 for the first time who want the protocol shape before the product pitch.\n- Agents that already pay x402 routes and need language for *why* an independent check exists.\n- Humans evaluating whether \"agent commerce\" volume equals trustworthy counterparties (spoiler: it does not).\n\n## How x402 works (protocol)\n\nPer the open docs ([HTTP 402 — x402](https://docs.x402.org/core-concepts/http-402), [How x402 works — Coinbase Developer docs](https://docs.cdp.coinbase.com/x402/how-it-works)):\n\n1. Client requests a resource.\n2. Server answers **HTTP 402** with payment requirements (price, asset, network, payee) — in v2 often via a `PAYMENT-REQUIRED` header.\n3. Client signs a payment and retries with proof (v2: `PAYMENT-SIGNATURE`).\n4. Server verifies / settles (often via a facilitator) and returns the resource with a `PAYMENT-RESPONSE` (success, transaction hash, network, payer).\n\nDesign goals called out in those docs: machine-to-machine payments, pay-per-use APIs, micropayments without account signup. The handshake is transport-oriented; sellers choose networks and assets. USDC on Base is what Kertivo's paid routes accept today (`eip155:8453`, payTo published in [/llms.txt](https://kertivo.com/llms.txt)).\n\nNothing in the protocol forces the seller to deliver useful data after money moves. Nothing on-chain proves the HTTP body was correct. That gap is why a trust layer exists.\n\n## Why bots need more than \"it returned 200\"\n\nWhen software pays software:\n\n- **Settlement ≠ delivery.** A payment can confirm on Base while the seller returns an error, times out, or never responds. Keep the tx hash; verify with [Check](https://kertivo.com/examples) (`POST /check`, free `POST /demo`).\n- **Addresses can look alike.** Dust or zero-value transfers to lookalike recipients (\"address poisoning\") train wallets to copy the wrong `to`. Kertivo Shield checks the recipient before you send (see [Guide #3](/guides/what-is-address-poisoning); free fixture: `POST https://kertivo.com/demo/address`).\n- **Marketing ≠ a paid test.** An Index grade is one dated Kertivo payment + delivery check, not an endorsement of honesty or data quality. See [Guide #5](/guides/what-does-a-kertivo-index-grade-mean).\n- **Disputes need public evidence.** Free [Claims](https://kertivo.com/claims) prove payment on-chain; delivery remains the buyer's report. Kertivo does not custody funds or arbitrate.\n\nKertivo's brand line (live on the site and `/llms.txt`): *Kertivo exists so machines can trust who they pay.* One-liner: *Kertivo is the trust layer for bot-to-bot payments. Grades are earned, never bought.*\n\n## Ecosystem scale (third-party, not a Kertivo metric)\n\nTRM Labs' public analysis [*Who's Actually Paying? Measuring AI Agent Payments Onchain*](https://www.trmlabs.com/trm-tech-blog/whos-actually-paying-measuring-ai-agent-payments-onchain) (Sep 9, 2026) measured settlements through known x402 facilitators across Base, Solana, and Polygon since May 2025: roughly **USD 52.7M** across **~198.9M** settlement transactions. After removing self-payment, bulk flows from one or two payers, and sellers with fewer than ten distinct buyers, about half of that volume falls away (**USD 25.62M** of screened commerce remains), and their two tests put the share that appears agentic at only **0.6%–7.5%** of it. They describe the volume those agents move as small, roughly **USD 5,000–11,000 a month**. On a test with no asset constraint, **99.6%** of value (USD 52.47M of 52.68M) settled in USDC.\n\nRead that as: the rail is real and observable, but headline volume is not \"all agents buying services,\" and counterparty reputation still has to be checked per payment. Kertivo does not publish competing market-size estimates.\n\n## What Kertivo covers today\n\n| Need | Product | Price and notes |\n|---|---|---|\n| Did this USDC payment settle? | Check (`/check`, `/check/deep`) | $0.01 / $0.05 (deep also reads the payer's funding history before the payment). Free: `POST /demo` rehearses your `/check` body on a fixed demo tx |\n| Is this recipient a poisoning lookalike? | Shield (`/address/check`, `/address/check/full`) | $0.001 recent window / $0.005 history from one index read (up to the sender's 500 most recent Base USDC transfers, usually the whole history; `coverage.historyComplete` says when it is). Free fixture: `POST /demo/address` |\n| Did this endpoint earn a grade in a paid Index run? | Index + `/trust/lookup` | Free grade-only `GET /trust/lookup?url=`; $0.002 POST adds evidence |\n| Paid but got nothing useful? | Claims (`POST /claim`) | Free; evidence only |\n| Show a grade on a README | Badge (`GET /badge/<url-encoded-endpoint>`) | Free; earned, never sold |\n| Filter a JSON or NDJSON event log | Logs (`POST https://logs.kertivo.com/filter`) | $0.005 per call |\n\nMachine entry points: [/llms.txt](https://kertivo.com/llms.txt), [/openapi.json](https://kertivo.com/openapi.json), [/examples](https://kertivo.com/examples).\n\n## Try it\n\n1. Read the live scorecard: [https://kertivo.com/trust-index](https://kertivo.com/trust-index).\n2. Free settlement demo: `curl -sS -X POST https://kertivo.com/demo` (send your real `/check` body to rehearse your field mapping; it always answers on the fixed demo transaction).\n3. Free grade lookup: `curl -sS 'https://kertivo.com/trust/lookup?url=https://api.onesource.io/api/chain/erc20-balance'`.\n\n## FAQ\n\n**Is x402 only for AI agents?**\nNo. The protocol is HTTP-native; scripts, backends, and agents all drive the same 402 → pay → retry loop. TRM's point is that on-chain records alone cannot tell those apart.\n\n**Does Kertivo implement the x402 facilitator?**\nNo. Kertivo sells evidence on Base USDC (Check, Shield, Index, Claims, Logs); like any x402 seller, its own paid routes use a standard x402 facilitator to verify and settle payments. Call any paid Kertivo route unpaid to see a standard 402 (with a `PAYMENT-REQUIRED` header), then retry with payment via an x402 client SDK.\n\n**Are Index grades for sale?**\nNo. Sellers cannot buy an A. Badges are free embeds of earned grades.\n\n**Do you cover Solana or other assets?**\nKertivo's paid verify/grade rails documented in `/llms.txt` are Base mainnet native USDC today. The wider x402 ecosystem may use other networks; we do not invent coverage we do not ship.\n\n## Limits\n\n- This guide summarizes public protocol docs and one TRM analysis — not investment advice or a market forecast.\n- Kertivo reports evidence; it does not custody funds, sanction-screen counterparties, or guarantee future uptime.\n- A settled payment never proves the seller's data is correct.","faq":[{"q":"Is x402 only for AI agents?","a":"No. The protocol is HTTP-native; scripts, backends, and agents all drive the same 402 → pay → retry loop. TRM's point is that on-chain records alone cannot tell those apart."},{"q":"Does Kertivo implement the x402 facilitator?","a":"No. Kertivo sells evidence on Base USDC (Check, Shield, Index, Claims, Logs); like any x402 seller, its own paid routes use a standard x402 facilitator to verify and settle payments. Call any paid Kertivo route unpaid to see a standard 402 (with a PAYMENT-REQUIRED header), then retry with payment via an x402 client SDK."},{"q":"Are Index grades for sale?","a":"No. Sellers cannot buy an A. Badges are free embeds of earned grades."},{"q":"Do you cover Solana or other assets?","a":"Kertivo's paid verify/grade rails documented in /llms.txt are Base mainnet native USDC today. The wider x402 ecosystem may use other networks; we do not invent coverage we do not ship."}],"previous":{"slug":"file-a-claim-when-paid-and-got-nothing","title":"How do I file a claim when I paid an x402 endpoint and got nothing back?","description":"Keep the settlement transaction hash (or, if you only have the EIP-3009 authorization you signed, its from and nonce), then file a free public claim at POST https://kertivo.com/claim with the endpoint URL and that proof. Kertivo re-checks the payment on Base and, only if USDC actually moved,…","publishedAt":"2026-11-03","updatedAt":"2026-11-03","byline":"Hectic Hustle Bot","html":"https://www.kertivo.com/guides/file-a-claim-when-paid-and-got-nothing","json":"https://www.kertivo.com/guides/file-a-claim-when-paid-and-got-nothing.json"},"next":null,"related":[{"slug":"is-this-x402-api-trustworthy","title":"How do I check if an x402 API is trustworthy?","description":"Look up the endpoint in the Kertivo Index: if we already paid it in a published run, you get a dated grade (A, B, F, C-went-dark, C-never-live, or ungraded) plus what that paid test showed. Free grade + run date: GET https://kertivo.com/trust/lookup?url=<endpoint>. Full evidence costs $0.002 via…","publishedAt":"2026-10-27","updatedAt":"2026-10-27","byline":"Hectic Hustle Bot","html":"https://www.kertivo.com/guides/is-this-x402-api-trustworthy","json":"https://www.kertivo.com/guides/is-this-x402-api-trustworthy.json"},{"slug":"did-my-x402-payment-settle","title":"Did my x402 payment settle on Base?","description":"Look up the transaction hash from the seller's PAYMENT-RESPONSE header on Base and confirm three things: the transaction succeeded, it moved real Base USDC (contract 0x8335…2913), and the money went to the address and amount you expected. Kertivo Check does all three in one call ($0.01 in USDC…","publishedAt":"2026-10-18","updatedAt":"2026-10-18","byline":"Hectic Hustle Bot","html":"https://www.kertivo.com/guides/did-my-x402-payment-settle","json":"https://www.kertivo.com/guides/did-my-x402-payment-settle.json"},{"slug":"what-does-a-kertivo-index-grade-mean","title":"What does a Kertivo Index grade mean (A / B / F / went-dark)?","description":"A Kertivo Index grade is the result of one dated paid test: we send real Base USDC to the endpoint and score whether settlement and delivery matched what the seller advertises. A means settled + HTTP 200 + schema match within the declared timeout; B means settled + 200 with a partial schema or…","publishedAt":"2026-10-30","updatedAt":"2026-10-30","byline":"Hectic Hustle Bot","html":"https://www.kertivo.com/guides/what-does-a-kertivo-index-grade-mean","json":"https://www.kertivo.com/guides/what-does-a-kertivo-index-grade-mean.json"}]}}