x402-examples

# x402 examples — pay-per-call APIs for AI agents

Working examples for calling [x402](https://x402.org)-gated HTTP APIs: your agent
pays **USDC per request on Base** — no signup, no API keys, no subscription.

All examples run against **[x402.shizu.me](https://x402.shizu.me)** (77 live
endpoints, prices from $0.001/call): an **OpenAI-compatible LLM gateway**
(`/v1/chat/completions`, `/v1/embeddings`, `/v1/models`), web search, a code
sandbox, web scraping, live crypto/market data, verifiable randomness, and a
**prepaid off-chain metering rail** for high-frequency loops (100+ calls/min,
no per-call gas).

## How x402 works

1. **Call** any endpoint → the `HTTP 402` response carries signed USDC payment
   requirements (price, asset, recipient).
2. **Pay** — your x402 client signs the payment locally and retries automatically.
3. **Served** — settlement is on-chain; you are only charged when the call
   succeeds. Errors and 4xx never settle.

Fund a wallet with a few dollars of USDC on Base, export its private key, and
every example here just works.

## JavaScript

```bash
npm install x402-fetch viem
export X402_PRIVATE_KEY=0x...   # wallet holding USDC on Base
node js/chat.mjs
```

## Python

```bash
pip install x402 eth-account httpx
export X402_PRIVATE_KEY=0x...
python python/chat.py
```

## Examples

| File | What it shows |
|---|---|
| [`js/chat.mjs`](js/chat.mjs) | OpenAI-compatible chat completion, paid per call |
| [`js/search.mjs`](js/search.mjs) | Live web search without a search-API account |
| [`python/chat.py`](python/chat.py) | Chat completion via the Python x402 client |
| [`python/embeddings.py`](python/embeddings.py) | OpenAI-shape embeddings for RAG loops |
| [`python/metered_loop.py`](python/metered_loop.py) | Prepay once, then 100+ calls/min off-chain |

## Just looking?

Every route quotes its price on a free unpaid request:

```bash
curl -i https://x402.shizu.me/crypto        # → 402 + payment requirements
curl https://x402.shizu.me/llms.txt          # full catalog, agent-readable
```

## Links

Live service: https://x402.shizu.me · OpenAPI: https://x402.shizu.me/openapi.json ·
MCP tools: https://x402.shizu.me/.well-known/mcp-tools · Contact: x402@opklaar.com

MIT licensed.