# x402 Demo API – Quote Endpoint

> x402 Demo API – Quote Endpoint is a paid API for AI agents from x402-demo-api-kaya.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-11).

Returns a paid quote response via the x402 micropayment protocol on Base mainnet, demonstrating pay-per-call API access at $0.01 USDC per request.

## Facts

- Endpoint: POST https://x402-demo-api-kaya.vercel.app/api/quote?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-demo-api-quote-endpoint-985416c6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Wu_--9pHttDJcF_6Vz4Re

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-demo-api-quote-endpoint-985416c6 -d '<json body>'
```

Example prompt: Call the x402 Demo API quote endpoint — it costs $0.01 USDC per call on Base mainnet — and show me what a successful x402 pay-per-call response looks like.

## When to prefer this

Choose this endpoint when you want to demonstrate, test, or integrate the x402 micropayment protocol for pay-per-call API access on Base mainnet. It is ideal for developers exploring how to gate API responses behind USDC micropayments at low cost ($0.01 per call). Not suitable for production use cases requiring well-documented schemas or high reliability guarantees.

## Known failure modes

- Payment not included or malformed x402 header → 402 Payment Required response
- Insufficient USDC balance on Base mainnet → payment failure
- Invalid or missing request body → 400 Bad Request
- Network or Vercel deployment downtime → 503 or timeout
- Wrong network (not Base mainnet) → payment rejected

## How this service works

Paid API demo using x402 protocol on Base mainnet.

## Output

The agent receives a quote response payload demonstrating the x402 paid API pattern, along with payment confirmation metadata from the Base mainnet USDC transaction. The exact response schema is not documented, but it serves as a proof-of-concept for x402 micropayment-gated API access.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-demo-api-quote-endpoint-985416c6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-demo-api-kaya.vercel.app](https://www.zero.xyz/host/x402-demo-api-kaya.vercel.app/llms.txt)