Use paid APIs like they were free.

curl "https://api.relai.fi/metered/x?url=https://api.example.com/data" \
  -H "X-API-Key: rpx_..."

PATCH https://api.relai.fi/metered/keys/rpx_...
{ "maxPerTransactionUsd": 1.00, "maxPerPeriodUsd": 50.00, "periodType": "daily" }

const PROXY = "https://api.relai.fi/metered/x";
const KEY  = process.env.RELAI_PROXY_KEY;

async function callX402(url, options = {}) {
  const res = await fetch(`${PROXY}?url=${encodeURIComponent(url)}`, {
    method: options.method || "GET",
    headers: { "X-API-Key": KEY, "Content-Type": "application/json", ...options.headers },
    body: options.body ? JSON.stringify(options.body) : undefined,
  });
  return res.json();
}

const data   = await callX402("https://api.example.com/data");
const result = await callX402("https://api.example.com/generate", {
  method: "POST",
  body: { prompt: "Hello world" },
});

import os, requests

PROXY = "https://api.relai.fi/metered/x"
KEY   = os.environ["RELAI_PROXY_KEY"]

def call_x402(url, method="GET", json=None):
    return requests.request(
        method, PROXY,
        params={"url": url},
        headers={"X-API-Key": KEY},
        json=json,
    ).json()

data   = call_x402("https://api.example.com/data")
result = call_x402("https://api.example.com/generate", method="POST",
                    json={"prompt": "Hello world"})

# GET
curl "https://api.relai.fi/metered/x?url=https://api.example.com/data" \
  -H "X-API-Key: $RELAI_PROXY_KEY"

# POST with JSON body
curl -X POST "https://api.relai.fi/metered/x?url=https://api.example.com/submit" \
  -H "X-API-Key: $RELAI_PROXY_KEY" \
  -H "Content-Type: application/json" \
  -d '{"key": "value"}'

Your Code              RelAI Proxy             x402 API
  |                       |                       |
  |--- GET /metered/x --->|                       |
  |   X-API-Key: rpx_...  |                       |
  |                        |--- GET /data -------->|
  |                        |<-- 402 Payment Req ---|
  |                        |                       |
  |                        |  [auto-sign payment]  |
  |                        |                       |
  |                        |--- GET + X-PAYMENT -->|
  |                        |<-- 200 OK + data -----|
  |                        |                       |
  |<-- 200 OK + data ------|                       |

{
  "apiKey": "rpx_a1b2c3d4...",
  "wallets": {
    "solana": { "address": "4KuwK7vP...", "network": "solana" },
    "evm":    { "address": "0x0787F7...", "networks": ["base", "skale-base", "avalanche"] }
  }
}

{
  "totalBalance": 10.50,
  "balances": {
    "solana":     { "balance": 5.00 },
    "base":       { "balance": 3.50 },
    "skale-base": { "balance": 2.00 },
    "avalanche":  { "balance": 0.00 }
  }
}