The price is in the response

Ask for a quote with no account and the endpoint answers 402 Payment Required, then names its price, its asset and where to send it. Pay, retry, get the route. Nothing was signed up for.

x402 docs The MCP server

Why 402 is the right shape

HTTP has had a status code for this since 1997. Nobody used it because nobody had a way to pay a machine.

Every other metering model assumes an account. A key issued in advance, usage piled against it, an invoice reconciled later. That works for a company. It does not work for a process that started ten seconds ago and will not exist tomorrow.

A 402 turns it around. The request carries no identity, the response carries the price, and payment settles per call. Nothing to provision, share or revoke, and no attribution problem afterwards. The payment is the accounting.

The exchange

Ask, get a price, pay it, get the route. Four messages, no signup in between.

terminalno key

# 1. ask, with no account and no key
curl -i -X POST https://app.ravn.exchange/api/v1/x402/quote \
  -H 'content-type: application/json' \
  -d '{"inputChainId":1,"outputChainId":-1, ... }'

HTTP/2 402
payment-required: eyJ4NDAyVmVyc2lvbiI6MiwicmVzb3VyY2UiOnsi...

# 2. decode it. the price, asset and payee are all in there
{
  "x402Version": 2,
  "accepts": [
    { "scheme": "exact", "network": "eip155:8453",
      "amount": "1000", "asset": "0x8335…2913",
      "payTo":  "0x12d2…6933", "maxTimeoutSeconds": 300 }
  ]
}

# 3. pay, retry with the receipt, get the route

What it costs

Endpoint	Price	What you get
`POST /api/v1/x402/quote`	0.001 USDC	A full parallel race across every eligible venue, returning a quoteToken.
`POST /api/v1/x402/execute`	0.01 USDC	Turns that quoteToken into a signable or broadcastable execution payload.

Read off a live 402 response, not a price list. The endpoint is the source of truth. Decode the payment-required header and you will see the same numbers.

Where it settles

Two networks, USDC on both. The agent pays from whichever it already holds.

Network	x402 identifier	Asset
Base	`eip155:8453`	USDC · 0x8335…2913
Solana	`solana:5eykt4Us…KvdP`	USDC · EPjFWdd5…TDt1v

It explains itself

The 402 also carries a bazaar extension: a full JSON Schema for the request body and an example response. An agent that has never seen this API can read the 402, learn the shape of a valid call and make one, with no human reading docs first.

That is what makes this more than a payment wrapper. The endpoint describes its own price and its own interface, in the same response.

x402 docs Agent suite

Or do not pay at all

The ordinary /api/v1/quote is free and anonymous at 30 requests a minute per IP, and the MCP server is free outright. x402 is here for agents that want their own metered access instead of a shared credential and a shared rate limit. It is not a toll on the rest.

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