Price ONE call to a catalog service WITHOUT paying it: it charges nothing, signs nothing and reserves no budget. Pass exactly what you would pass to pay_service (the same slug, path, method, search, headers, body and delegationId): the Router sends that request to the service unpaid, reads the price it asks for, and returns an opaque quoteId, its short expiresAt, the rail (protocol), the network and merchant amount (settlement) and the fee-inclusive total (fee.capChargedCents, whole cents rounded up; fee.capChargedMicros exact, in 1/10,000 of a cent). Unlike the quote on a get_service endpoint (the last merchant price the catalog observed, routing fee excluded), this is priced live for your exact request and includes the fee. Because the request really reaches the service, a service that does not charge for it performs it, so take care quoting a method with side effects; and a quote spends the same per-service rate limit as a payment, so quote once per decision rather than polling. It prices the delegation pay_service would charge (optionSet: "delegation", naming its delegationId), or, with no delegation set up, what a personal crypto delegation would select (optionSet: "deployment"); in that case nextTool is setup_delegation: set one up and quote again before paying, since the delegation you create can select a different rail and price. It checks neither your remaining budget nor your wallet balance (see get_budget and wallet_balance). Next step (nextTool: "pay_service"): if fee.capChargedCents fits what you planned to spend, call pay_service before expiry with the same arguments, the quoted delegationId, quoteId, and maxTotalCents set to that figure as a number. The quote id fixes the exact challenge and fee-inclusive total while maxTotalCents remains an independent ceiling. paymentRequired: false means the service did not ask for payment for this request; upstreamStatus is its answer, and a non-2xx usually means the path, method or body is wrong. The service response itself is never returned. Outcomes, all charging nothing: {"payable":false}, service_not_found, catalog_unavailable and delegation_lookup_failed as in pay_service; quote_unavailable (no quote can be made here and retrying will not change that, so bound the price with pay_service maxTotalCents instead); quote_failed (the Router refused to price the call, or did not answer; see code, message and retryable); credential_refused (re-authorize). FUNDING (funding): chosen as pay_service would choose it. When you hold Nevermined credits that can pay it (a Nevermined Subscription allowance, welcome or top-up credits) and the endpoint accepts credits the answer is {"funding":"subscription","credits":…,"paymentRequired":…,"upstreamStatus":…}: the exact credits this request costs (the service is sent it unpaid; there is no quoteId or cent total). Credits follow each service’s live price, with a 1-credit minimum, so pass everything pay_service will send. Then call pay_service with the same arguments and the maxCredits this answer gives: a call that has become dearer is refused and charges nothing. paymentRequired: false means the service named no price for this request, and credits is then 0. The credits left of a subscriber in good standing are checked only when pay_service makes the call, so this answer does not promise the call will be paid with credits. Pass funding: "delegation" to price the delegation instead. Subscription refusals are named as in pay_service. When settlement.scheme is session, the merchant is paid out of a deposit in a payment channel, and sessionDeposit says what this call would do to it: action is open (the first call locks a deposit), top_up (it locks more), none (no new money leaves the wallet), closing (the call would be refused, nothing moves; quote again once it has closed) or null (what the call would do could not be stated, and pay_service may refuse it); approxCents is how much would move into the deposit, in cents, the network fee not included, and basis says whether that is sized for this budget and wallet or an upper_bound. That money can far exceed the price. It is locked, not spent, it is not charged to the budget, and what the merchant does not take comes back when the channel closes, idleCloseSeconds after its last use. Tell the human before paying. Requires your Nevermined API key on the Authorization header.