# x402 Live Probe

> x402 Live Probe is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-20).

Validates and measures a third-party x402 payment endpoint by performing a live GET/402 handshake, checking contract fields, and returning a signed observation receipt — without making any payment.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/live-probe?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-live-probe-98c74c01
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_aMXIvPvVGJC_DbU6r7vq5

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 x402-live-probe-98c74c01 -d '<json body>'
```

Example prompt: Before I pay, can you probe the x402 endpoint at https://api.example.com/paid-service to check its payment contract is valid — confirm the price, network, and expiry look right and give me a signed observation receipt?

## When to prefer this

Use this endpoint when an AI agent needs to verify a third-party x402 endpoint is live and contract-compliant before committing any payment. It is the right choice when you want a timestamped, signed receipt as audit evidence, when you need to check price/network/expiry fields against the x402 spec without side effects, or when building a directory or marketplace that needs to track endpoint health. Prefer this over simply calling the paid endpoint speculatively, as it incurs no payment and produces a citable observation record.

## Known failure modes

- Endpoint is unreachable or times out — probe returns failure with no contract data
- Endpoint returns a malformed or non-compliant 402 response — validation fails with field-level errors
- URL is not HTTPS or is malformed — rejected before handshake
- Endpoint contract fields (price, expiry, network) fail x402 spec validation — returned with specific violation details
- Rate limiting or transient network errors — probe may fail intermittently

## How this service works

Verify any third-party x402 endpoint is alive and correctly configured
before paying it: a bounded GET/402 preflight fetches the payment contract,
checks reachability and response latency, validates accepts, network, price
and expiry against the x402 spec, and returns a signed observation receipt
with an observed_at timestamp you can cite — protection against ghost
endpoints, dead quotes and wasted USDC.
Limitation: no payment is made, one endpoint per call, and a passing probe
proves the contr…

## Output

A signed observation receipt containing: validation pass/fail status, the observed payment contract details (price, accepted payment methods, network, expiry), measured response latency, and an observed_at timestamp. The receipt is signed so it can be cited as evidence of endpoint state at observation time.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "maxLength": 2048,
   "minLength": 12,
   "description": "Single https x402 endpoint to handshake. One URL per call; no payment is sent."
  },
  "capability": {
   "type": "string",
   "maxLength": 120,
   "minLength": 1,
   "description": "Optional capability tag stored on the observation receipt for later directory queries."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "url": "https://api.example-x402.test/pay",
  "kind": "x402_live_probe",
  "paid": false,
  "latency_ms": 42,
  "receipt_id": "0000000000000000000000000000000000000000000000000000000000000000",
  "http_status": 402,
  "observed_at": "2026-08-14T19:00:00+00:00"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-live-probe-98c74c01/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)