# PayerProof Trust Score API

> PayerProof Trust Score API is a paid API for AI agents from payerproof-production.up.railway.app, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-30).

Computes a 0-100 trust score for an x402 service listed in the Bazaar, combining liveness, on-chain payer diversity, revenue verification, and listing age into a graded report with flags.

## Facts

- Endpoint: POST https://payerproof-production.up.railway.app/score?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/payerproof-trust-score-api-8c256b20
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_pF0Z33YbUEspMZ-S_6_3V

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability payerproof-trust-score-api-8c256b20 -d '<json body>'
```

Example prompt: Before I start using this paid x402 API at https://api.example.com/paid, can you run a PayerProof trust score on it and tell me the grade, any red flags like concentrated payers or inflated revenue, and the breakdown of each component?

## When to prefer this

Use this endpoint when you need to vet the credibility of a specific x402 service before integrating it or paying for its calls, especially when suspicious of inflated revenue counters, self-dealing, or low payer diversity. It is the right choice over generic on-chain lookup tools because it combines liveness, payer diversity, revenue verification, and listing age into a single graded trust score tailored to the Bazaar/x402 ecosystem.

## Known failure modes

- Resource URL not found in Bazaar listings — returns error indicating unrecognized listing
- Service is unreachable during liveness probe — liveness component fails, score reduced
- On-chain data unavailable for the seller address — revenue verification component incomplete
- Invalid or malformed resource URL input — returns validation error
- Rate limit or payment failure for the $0.02 USDC per-call fee — request rejected

## How this service works

Trust score (0-100) for an x402 service listed in the Bazaar: liveness probe, on-chain payer diversity, reported-vs-verified revenue (detects inflated counters and self-dealing), and listing age. Returns full component breakdown and flags.

## Output

A JSON object containing a numeric trust score (0-100), a letter grade (e.g. A, B, C), a list of warning flags (e.g. concentrated_payers, inflated_revenue, self_dealing), and a full component breakdown covering liveness probe result, listing age, payer diversity metrics, and reported-vs-verified revenue comparison.

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "flags": [
   "concentrated_payers"
  ],
  "grade": "B",
  "score": 72,
  "resource": "https://api.example.com/paid",
  "components": {
   "liveness": {},
   "listingAge": {},
   "payerDiversity": {},
   "revenueVerification": {}
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/payerproof-trust-score-api-8c256b20/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from payerproof-production.up.railway.app](https://www.zero.xyz/host/payerproof-production.up.railway.app/llms.txt)