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Agents can buy a single CrakSEO data call without an account, an API key or prepaid credits. Each paid data tool has its own endpoint that accepts the Machine Payments Protocol (MPP): the first request returns the exact price, the agent pays, and the retry returns the data with a payment receipt.
A daily budget caps keyless calls. When it is used up, endpoints answer 429 with budget_exceeded until the next UTC day, and nothing is charged. Accounts with API credits can call the same tools at any time.

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How a call works

  1. Send the request. POST https://crakseo.com/api/v1/mpp/<tool> with the tool’s JSON input, for example:
  2. Read the quote. The response is 402 Payment Required with one WWW-Authenticate: Payment ... challenge per payment method. The challenge is bound to this endpoint and amount and expires after a few minutes. Nothing is charged yet.
  3. Pay and retry. Send the same request again with Authorization: Payment <credential>. MPP clients such as mppx or a Link wallet do this step for you.
  4. Get the data. CrakSEO runs the call once, then settles the payment and returns 200 with { result, billing } and a Payment-Receipt header. A failed call is never settled, so you only pay for data you receive.
One payment buys one call. A credential that was already used is refused, even if the first attempt failed.

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Prices

The price is fixed before the call from the request’s inputs (for example result depth, number of keywords or limit), and is at least $0.01. The 402 challenge always carries the exact amount. The OpenAPI document lists every endpoint with the price of an example request. Repeated identical requests within 24 hours may be answered from cache at the same price.

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Responses

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Limits

  • Requests are rate limited per IP address and per paying wallet, and per-call capacity has a daily ceiling. A 429 includes Retry-After.
  • Inputs have the same caps as the API, for example up to 5 URLs per site audit, 10 keywords per rank check and 200 keywords per search-volume call.
  • Free tools are not sold per call: the Search Console MCP, free URL submission and index checks, and the credit balance. Force indexing is not sold per call either; it needs an exact quote and the account owner’s approval.

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Endpoints

Every endpoint takes the same JSON input as the matching MCP tool (see the tool reference).

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Per call or API credits?

Per-call payments suit an agent that needs a few calls and has an MPP wallet. For regular use, an account with API credits is simpler: one balance for every MCP server, REST call and dashboard run, a usage history, and no payment step per call. Per-call payments never touch an account’s credits.