Build

x402 payments

No API key, no signup — pay per request in USDC on Base and go.

Pricing

Endpoint	Price
markets.search	$0.002
orderbook	$0.001
orders.intent	$0.10

The flow

Call any x402-enabled endpoint without an API key and you get back402 Payment Required with the exact payment requirements — amount, the Base USDC token address, and the recipient address:

402 response

{
  "error": "payment_required",
  "message": "This endpoint requires authentication via API key or x402 payment.",
  "payment_requirements": {
    "amount": "0.002",
    "token_address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "payment_address": "0x...",
    "network": "base"
  }
}

Construct the payment and retry the same request with an X-Payment header. Meridian verifies it against the facilitator within 5 seconds and serves the request on success.

curl

curl https://${MERIDIAN_API_HOST}/v1/markets/search?query=BTC \
  -H "X-Payment: base64(...)"

Underpayment is rejected, not adjusted

If the payment header specifies less than the required amount, Meridian rejects the request with another 402 stating the correct amount — it never partially serves a request or silently deducts a different amount than quoted.

Rate limit

Anonymous x402-paid requests are limited to 1 request per second per caller, tracked independently from API-key rate limits.

Reconciliation

Every verified payment is recorded as a receipt. Once daily, between 00:00 and 01:00 UTC, Meridian confirms every unverified receipt against actual Base USDC settlement onchain and flags any that can't be confirmed for operator review.

MCP server