# Pizza Ex Machina > A pizzeria for AI agents: a priced menu over one HTTP API, with real pizzas prepared and delivered by kitchen partners across the US. Flat prices include delivery, tip, and tax; quotes are free. Pizza Ex Machina's API is available to AI agents as a pay-per-use endpoint. Send the upstream API's paths to `https://agents.pizzaexmachina.com` and the endpoint handles identity, payment, and proxying. There is no signup and no API key: agents pay per use with a range of payment methods (x402 and MPP today), autonomously or with their human's approval. Document version: `97f9df88949e`. The same value is the `version` field of https://agents.pizzaexmachina.com/manifest.json, which is generated live. If the two differ, this copy is stale - discard it and refetch this URL before relying on anything below, especially prices and payment methods. ## No payment method? You can set one up - no signup Payment challenges are signed with an EVM wallet. If you or your operator already have one, settle challenges with your usual x402 or MPP client. If you are an autonomous agent without one, you can create an account and managed wallet yourself - no signup, at no cost: `npm i -g @zeroxyz/cli && zero auth agent register`, then `zero fetch https://agents.pizzaexmachina.com/` settles 402 challenges for you. The account can be handed to a person at any time with `zero auth agent claim `, so nothing is locked to the agent. Follow your own instructions about when to involve a human - this API works the same whether you pay autonomously or after checking in. Funding and manual setup: [agent guide](https://agents.pizzaexmachina.com/llms-full.txt). ## Using this API - [Agent guide](https://agents.pizzaexmachina.com/llms-full.txt): how to authenticate, handle the 402 payment challenge, and call every endpoint. Read this first. - [Live pricing catalog](https://agents.pizzaexmachina.com/manifest.json): the current services, meters, plans, prices, and free included units as JSON. Read it at call time; do not cache prices. - [Identity for plan purchases](https://agents.pizzaexmachina.com/auth.md): buying a plan requires a bearer credential - register once (free, no email needed to start); the same credential works at every storefront on this network. Pay-as-you-go needs none. - [API reference (upstream OpenAPI)](https://api.pizzaexmachina.com/openapi.json): the operations, paths, and request/response schemas. Call these paths through `https://agents.pizzaexmachina.com`, never the upstream directly. ## Payment methods - [x402 quickstart for buyers](https://docs.x402.org/getting-started/quickstart-for-buyers): settle x402 challenges (Base USDC) with `@x402/fetch`, `@x402/axios`, or the `x402` package on PyPI. - [MPP credentials](https://mpp.dev/protocol/credentials): settle MPP challenges (Tempo USDC) by signing a credential and sending it as an `authorization` bearer header. - Credit/debit cards (plan purchases only): register an agent identity ([auth.md](https://agents.pizzaexmachina.com/auth.md)), then send the purchase with `Authorization: Bearer` and one of `checkout: true` (needs no funds and no card - returns a hosted payment URL to deliver to your human; always available as the fallback when you cannot pay yourself), `stripePaymentMethodId`, or `sharedPaymentToken` - the purchase 402's `card` block lists the exact fields and tokenization coordinates. ## Ceiling pricing - charging up to a maximum Some meters (e.g. output tokens) cannot be known before the work runs. The 402 challenge then lists the item as {"meterSlug", "maxQuantity"} and the payment amount is a CEILING, not the price you pay - it is the most you could ever be charged, and you pay only your actual usage once the work runs (the seller may set the ceiling per request, or configure a per-meter default that applies when a request declares no maxQuantity). A ceiling-priced request settles on the RESERVE-AND-PAY-ACTUAL rails by design: your wallet reserves the ceiling up front, then you are charged only actual. Each rail is an entry in the challenge (look for the "billing" note in the entry's extra): the x402 "upto" scheme (Base USDC), where the reserved remainder simply never leaves your wallet, and the MPP "session" escrow channel (Tempo USDC), where you fund a channel to the ceiling, sign one voucher, and the payment proxy closes the channel at your actual usage so the escrow refunds the rest - and if it ever fails to close the channel, you can force-close it yourself after the on-chain grace period to reclaim your full deposit, so escrowed funds are never stranded. One-shot prepay ("exact", the MPP charge) is never offered for a ceiling-priced request; that is what guarantees an unspent ceiling can never get stuck as seller credit. (If you already hold a prepaid balance with this seller from a plan purchase, ceiling-priced usage can still draw it down - billed at actual, like everything else; how to purchase a balance is in the agent guide linked above.) A failed delivery debits nothing on either rail. Fixed-quantity requests are unchanged: pay "exact" or the one-shot MPP charge as always. Either way you are never charged past the ceiling, and never the full ceiling unless your usage actually reaches it. Every paid response also carries a `zc-billing` header reconciling the numbers for that request: what you authorized, what you were actually charged, the remainder and where it went ("status":"settled"), or "status":"settling" when on-chain settlement is still finishing. ## Optional - [Storefront](https://agents.pizzaexmachina.com/): human-readable overview and plans. - [Upstream docs](https://pizzaexmachina.com/docs) - [Upstream llms.txt](https://pizzaexmachina.com/llms.txt) - [Website](https://pizzaexmachina.com)