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The Machine Payments Protocol (MPP) is an open standard for machine-to-machine payments over HTTP. Xquik accepts direct MPP payments on 7 fixed-price read operations. You can call them without an account, API key, or subscription.

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How it works

MPP uses HTTP 402 (Payment Required) as a payment challenge. When you call a direct MPP operation without authentication, the server returns an application/problem+json response and a WWW-Authenticate: Payment header. Your client pays through Tempo (USDC), then retries the request with a payment credential.
Every response after an accepted payment includes Payment-Receipt, including non-2xx responses. The receipt confirms settlement, not application success. Challenges and rejected payment credentials do not include a receipt.
The same 402 body also advertises an optional accountless guest wallet. The MPP challenge remains unchanged. A failed read creates no checkout. Create a hosted checkout only after the user confirms an amount. No account, API key, or subscription is required. The payment credential authenticates the retried request.

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Payment method

MPP payments on Xquik use Tempo with USDC, a dollar-pegged stablecoin. Tempo provides the settlement method for these fixed charges. You need a funded Tempo USDC wallet. See the MPP quickstart for setup instructions.

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Discovery

MPP discovery metadata is available at:
The document points clients to the live OpenAPI spec and MPP overview page.

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Payment intent

All direct MPP operations use the charge intent. Each accepted payment settles the fixed price for one request. Xquik does not advertise direct MPP session pricing for result-sized pages.

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Eligible endpoints

An accountless guest wallet covers 33 prepaid GET routes, including these 7. See the guest paid-read route inventory. Direct MPP payment credentials and guest keys cannot access monitors, webhooks, extractions, draws, writes, account routes, or account credential routes. API MCP cannot execute guest wallet credential routes.

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MPP vs subscription

CapabilityMPPGuest walletAccount
Account requiredNoNoYes
CredentialPer-request payment credentialpaid_reads API keyFull API key or OAuth token
PaymentPer request via Tempo (USDC)10−10-250 USD hosted checkoutAvailable account credits; plans add monthly credits
Available endpoints7 fixed-price GET operations33 prepaid GET routesFull account API
Write actionsNot availableNot availableAvailable with a connected X account
Monitors, webhooks, extractions, and drawsNot availableNot availableAvailable
Best forMachine-paid requestsPrepaid reads without an accountFull platform workflows

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Next steps

MPP quickstart

Make your first pay-per-use API call.

Authentication

All authentication methods including MPP headers.

Billing & usage

Subscription, guest wallet, and direct MPP pricing.

Guest wallets

Prepay 33 accountless reads with one scoped API key.