vet402 — Independent Verification of the x402 Agent-Payment Economy
We buy. We settle. We publish the measurements.
Abstract
vet402 buys what x402 endpoints actually sell, verifies fulfillment against the seller’s own declaration, and publishes the results with evidence. Every verdict will carry a transaction hash, a timestamp and reproduction steps. Nothing on this site is an estimate.
1.The problem this memo addresses
x402 settles payments finally and irreversibly. Proof of payment exists on-chain. Proof of delivery does not exist anywhere.
Registries can be written for cents: 98.7% of ERC-8004 reputation feedback has no verifiable transaction behind it. [ARXIV-2606]
Directory metrics can be manufactured: roughly half of observed x402 traffic is self-dealing. [ARTEMIS-2026]
2.Verification levels
Four levels, in order of what they cost us to run and what they prove. A result never moves up a level: an L0 probe cannot report settlement, and an L3 opinion is never folded into an L0–L2 fact.
- L0 Liveness
Does the endpoint answer correctly?
How: Probe, no purchase
Output: pass / fail / unverified
- L1 Settle-through
Does payment settle and a response arrive?
How: Real purchase
Output: n of m settled, latency
- L2 Conformance
Does the response match the seller's own declaration?
How: Purchase + machine diff
Output: conform / mismatch / undeclared
- L3 Quality
Is the content any good?
How: Published rubric
Output: opinion — never mixed with L0–L2
3.What a verdict must carry
A failing verdict publishes with raw log, transaction hash, timestamp and reproduction steps — or it does not publish.
Unverifiable is not a verdict. We say “unverified”, never “bad”.
Sellers can dispute any result and trigger a free re-verification. Corrections are logged publicly.
4.Implemented and live
Everything in this section is running right now and can be checked without asking us.
Verified Payee
Prove control of a wallet by signature, get a public verification page and an SVG badge.
Drop-in middleware, REST API and MCP tool
An x402 middleware package, a REST API, and an MCP tool that answers the question a spending agent should ask before it pays.
Public accuracy ledger
Every past verdict and its outcome, misfire rate included — published whether or not the numbers flatter us.
5.Status of this work
Under construction, in the open. These are not measurements yet, and this page will not describe them as though they were.
The observatory
A continuous catalog of x402 endpoints across chains, probed daily, with delisting alerts for claimed sellers.
Writing to the empty registry
Verification records will be written to the ERC-8004 Validation Registry — the one registry that is still empty.
Follow the build
A.Access tiers
Usage-based. The free tier is enough to wire a check into an x402 flow and see real results before committing to anything.
| Tier | Price | Lookups / month | Includes |
|---|---|---|---|
| Free | $0 | 1,000 | REST, MCP and x402 middleware, TypeScript SDK |
| Pro | $49/mo | 50,000 | Everything in Free, plus score history and priority support |
| Scale | $199/mo | 500,000 | Everything in Pro, at the highest rate limit |
Paid tiers are upgraded from the dashboard once a key exists. No card is required to start.
B.References
- [ARXIV-2606]
- 98.7% of ERC-8004 reputation feedback has no verifiable transaction behind it. arXiv:2606.26028
- [ARTEMIS-2026]
- Roughly half of observed x402 traffic is self-dealing. Artemis, x402 activity analysis, 2026.