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

Working examples for calling x402-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 (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

Call any endpoint → the HTTP 402 response carries signed USDC payment requirements (price, asset, recipient).
Pay — your x402 client signs the payment locally and retries automatically.
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

Terminal

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

Python

Terminal

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

Examples

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

Just looking?

Every route quotes its price on a free unpaid request:

Terminal

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.