| Availability (valid 402 returned) | 100.0% of 61 probes · single vantage |
| Median 402 handshake | 363ms |
| p90 handshake | 543ms |
| Catalog price (advertised) | $0.05 |
| Live price (median demanded) | $0.05 |
| Price status | match |
| Protocol | x402 v2 |
| Category (our classification) | security-infra |
| Payment receiver | 0xce53…1342 · stable since Jul 12 |
| Base USDC inflow to this receiver wallet (30d, all sources — not just x402) | none observed |
| Discovery (.well-known/x402) | not found |
| Catalog volume (their metric) | 2 calls/30d |
Compare 1-10 DOI-bearing references against Crossref metadata: supplied title, ordered authors and/or year. Returns field agreements, discrepancies, ambiguities and provenance; does not verify scientific claims. 0.05 native USDC per completed batch on …
What this grade does and doesn't measure: it scores the paid-request handshake — whether the service returns a spec-valid 402 payment challenge, how fast, and whether its price is honest. We do not pay these endpoints yet, so we do not verify that the paid response returns correct or complete content. Availability is a probe success rate measured hourly, from a single network vantage for this service.
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