# CURB Discovery Probe (x402 USDC on Base)

> CURB Discovery Probe (x402 USDC on Base) is a paid API for AI agents from api.curb.numetal.xyz, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-15).

A paid discovery probe endpoint that validates x402 USDC micropayment flow on Base, returning a confirmation response upon successful payment

## Facts

- Endpoint: POST https://api.curb.numetal.xyz/v1/matches/match_mrerora1_ef4aa28e/pay
- Price: $0.1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/curb-discovery-probe-x402-usdc-on-base-0ba5112b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Qn8svYPK143LqOf8jiyfu

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 curb-discovery-probe-x402-usdc-on-base-0ba5112b -d '<json body>'
```

Example prompt: Send a discovery probe to the CURB x402 endpoint on Base — pay the $0.10 USDC fee and include the note 'testing integration' to confirm the payment flow works end to end.

## When to prefer this

Use this endpoint when you need to verify that an x402 USDC micropayment integration on Base is functioning correctly, or when discovering and probing CURB API capabilities via a low-cost ($0.10) test transaction. Prefer this over free probes when you need to confirm the full paid payment flow end to end.

## Known failure modes

- Payment not received or insufficient USDC balance — 402 Payment Required returned
- Invalid x402 payment header format — 400 Bad Request
- Base network congestion causing payment timeout
- Match ID not found — 404 Not Found
- Duplicate payment attempt rejected — idempotency violation

## How this service works

CURB discovery probe — USDC x402 on Base (sample price)

## Output

Upon successful USDC payment via x402 on Base, the endpoint returns a probe confirmation response for the specified match ID, validating that the micropayment pipeline is operational.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "note": {
   "type": "string",
   "description": "Optional; ignored on unpaid probe."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/curb-discovery-probe-x402-usdc-on-base-0ba5112b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.curb.numetal.xyz](https://www.zero.xyz/host/api.curb.numetal.xyz/llms.txt)