{"catalog":{"getX402Primer":{"type":"explainer","zfiniaPublishedAt":"2026-09-07T00:00:00.000Z","updatedAt":"2026-09-07T00:00:00.000Z","evidenceTier":"TIER_B","newsroomState":"PUBLISHED","id":"what-is-x402","slug":"what-is-x402","title":"What is x402?","dek":"An open protocol that uses HTTP 402 so a client can pay a server, usually in USDC, and retry.","body":["x402 is a payment protocol introduced publicly by Coinbase on 6 May 2025. A server that wants to charge for a resource responds with HTTP 402 and machine-readable payment requirements. A client that can pay attaches proof and repeats the request.","The protocol is named for the reserved HTTP status “Payment Required.” x402 does not invent a new status code. It specifies what a 402 means to a machine, typically via headers, and how settlement is verified through a facilitator.","Foundry’s first production rail uses exact USDC payments on Base mainnet through the authenticated Coinbase CDP facilitator. That is a policy choice. The protocol documentation also lists other networks and facilitators."],"sources":[{"name":"Coinbase","url":"https://www.coinbase.com/developer-platform/discover/launches/x402"},{"name":"x402 seller quickstart","url":"https://docs.x402.org/getting-started/quickstart-for-sellers"}]},"getMCPPrimer":{"type":"explainer","zfiniaPublishedAt":"2026-09-07T00:00:00.000Z","updatedAt":"2026-09-07T00:00:00.000Z","evidenceTier":"TIER_B","newsroomState":"PUBLISHED","id":"what-is-mcp","slug":"what-is-mcp","title":"What is MCP?","dek":"A standard way for models to list and call tools. It is not itself a payment protocol.","body":["The Model Context Protocol, open-sourced by Anthropic on 25 November 2024, defines how a host (the model runtime) talks to servers that expose tools, resources and prompts.","MCP solved a proliferation of one-off integrations. It did not solve billing. tools/list and tools/call tell an agent what it can do, not what it owes."],"sources":[{"name":"Anthropic","url":"https://www.anthropic.com/research/model-context-protocol"}]},"getMachineCommerceGuide":{"type":"explainer","zfiniaPublishedAt":"2026-09-07T00:00:00.000Z","updatedAt":"2026-09-07T00:00:00.000Z","evidenceTier":"TIER_B","newsroomState":"PUBLISHED","id":"what-is-the-machine-economy","slug":"what-is-the-machine-economy","title":"What is the machine economy?","dek":"Software that discovers, pays, works and settles with other software — with humans setting budgets and rules.","body":["The machine economy is the emerging layer of the internet where agents and services transact with each other: they discover a capability, understand its contract, pay if required, use the result, and leave an audit trail.","It is not a meme-coin casino and it is not “AI slop media.” The economically important parts are boring on purpose: schemas, prices, payment challenges, settlement, provenance and retries.","Humans still matter. They fund wallets, set policy, sue people, and write the standards. The new behaviour is that a machine can complete a paid request without a checkout page or a sales call."],"sources":[{"name":"Coinbase x402 launch","url":"https://www.coinbase.com/developer-platform/discover/launches/x402"},{"name":"Stripe MPP","url":"https://stripe.com/blog/machine-payments-protocol"}]},"getAgentWalletGuide":{"type":"explainer","zfiniaPublishedAt":"2026-09-07T00:00:00.000Z","updatedAt":"2026-09-07T00:00:00.000Z","evidenceTier":"TIER_B","newsroomState":"PUBLISHED","id":"what-is-an-agent-wallet","slug":"what-is-an-agent-wallet","title":"What is an agent wallet?","dek":"A spending envelope a machine can use, with policy, not a seed phrase pasted into a prompt.","body":["An agent wallet is a credential and policy surface that lets software spend under constraints: asset, network, counterparties, per-payment cap, total cap, kill switch.","Visa Intelligent Commerce wraps this as a tokenized card with user instructions. x402 payers wrap it as a wallet that can sign exact payments. MPP wraps it as credentials that can settle in cards or stablecoins.","If a system requires a human to paste a seed phrase into a chat, it is not a production agent wallet. It is an incident waiting to happen."],"sources":[{"name":"Visa Intelligent Commerce","url":"https://developer.visa.com/use-cases/visa-intelligent-commerce-for-agents"},{"name":"Coinbase AgentKit","url":"https://github.com/coinbase/agentkit"}]},"getProtocolComparison":{"id":"x402-vs-mpp","slug":"x402-vs-mpp","type":"lesson","title":"x402 vs MPP","dek":"Two HTTP 402 families. Different payloads, facilitators, and settlement stories.","body":["x402, launched publicly by Coinbase in May 2025, typically settles stablecoins through a facilitator such as CDP. MPP, co-authored by Stripe and Tempo in March 2026, is designed to be rail-agnostic including cards and stablecoins into existing merchant balances.","Cover both. Do not pretend they are the same protocol. Routing is a product."]},"getDiscoveryChecklist":{"title":"Machine discoverability checklist","items":["Outcome-oriented description","Input and output JSON Schema","Exact price, asset, network, payTo","Live 402 matches advertised terms","OpenAPI and/or well-known and/or MCP tools/list","No metadata stuffing that breaks buyer clients","Provenance and limitations on the result","Usage rights a machine can read"],"lesson":"MORE METADATA IS NOT AUTOMATICALLY BETTER. Protocol conformance outranks keyword stuffing."},"getBuildGuide":[{"slug":"build-your-first-paid-agent-service","title":"Build your first paid agent service"},{"slug":"build-your-first-x402-api","title":"Build your first x402 API"},{"slug":"turn-existing-api-into-agent-service","title":"Turn an existing API into an agent-purchasable service"},{"slug":"build-your-first-mcp-tool","title":"Build your first MCP tool"},{"slug":"make-an-agent-buy-an-api","title":"Make an agent buy an API"},{"slug":"give-an-agent-a-safe-spending-budget","title":"Give an agent a safe spending budget"},{"slug":"buy-add-value-sell","title":"Build a buy → add value → sell workflow"},{"slug":"make-service-discoverable-by-agents","title":"Make your service discoverable by other agents"}],"workflow":["OBSERVE","FIND_DEMAND","FORM_HYPOTHESIS","BUILD_MINIMUM_SERVICE","MAKE_IT_MACHINE_DISCOVERABLE","PRICE_IT","TEST_WITH_REAL_BUYERS","MEASURE_REPEAT_USE","IMPROVE_OR_KILL"],"helloX402":{"id":"hello-x402","title":"Hello x402","architecture":"Unpaid POST → HTTP 402 challenge. Paid retry → deterministic JSON transform. No private keys in the reference.","setup":"Copy handleHelloX402 into any HTTP server. Point payTo at your receive address. Use a real facilitator only in production.","schemas":{"input":{"type":"object","properties":{"text":{"type":"string","minLength":1,"maxLength":2000}},"required":["text"],"additionalProperties":false},"output":{"type":"object","properties":{"text":{"type":"string"},"length":{"type":"integer"}},"required":["text","length"]}},"paymentFlow":"discover schema → POST → 402 → pay exact USDC on Base → retry → 200 JSON","expectedCost":"$0.001 per call at 1000 atomic USDC, plus network fees paid by the buyer wallet — not by this reference.","security":["Do not put a seller private key in the server.","Do not paste a seed phrase into an agent prompt.","Validate input before settlement in production paid paths."],"testing":"node --test test/zfinia-learn.test.mjs","discovery":{"wellKnown":false,"educational":true,"notFoundryProductionRoute":true},"deployment":"Educational snippet. Do not deploy this as a Foundry production product without the full receive-only gates."},"challengeExample":{"x402Version":2,"accepts":[{"scheme":"exact","network":"eip155:8453","asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","amount":"1000","payTo":"0x25e8245f07d5e4873987293dad666afbe56a9608","maxTimeoutSeconds":60}],"resource":"/learn/refs/hello-x402","description":"Deterministic echo+length transform. Educational reference, not a Foundry production route."}},"lessons":[{"slug":"what-is-an-ai-agent","title":"What is an AI agent?","dek":"Software that can take a goal, use tools, and act — not a chat window with a personality."},{"slug":"what-is-the-machine-economy","title":"What is the machine economy?","dek":"Software that discovers, pays, works and settles with other software — with humans setting budgets and rules."},{"slug":"what-is-x402","title":"What is x402?","dek":"An open protocol that uses HTTP 402 so a client can pay a server, usually in USDC, and retry."},{"slug":"what-is-mcp","title":"What is MCP?","dek":"A standard way for models to list and call tools. It is not itself a payment protocol."},{"slug":"what-is-a-machine-payment-rail","title":"What is a machine-payment rail?","dek":"The rules, asset, network and verifier that let software settle without a checkout page."},{"slug":"why-agents-pay","title":"Why would one agent pay another?","dek":"Because fetching, verifying, or computing something is cheaper than guessing."},{"slug":"what-can-an-agent-sell","title":"What can an agent sell?","dek":"A deterministic or bounded result with a schema, a price, and usage rights."},{"slug":"what-is-an-agent-wallet","title":"What is an agent wallet?","dek":"A spending envelope a machine can use, with policy, not a seed phrase pasted into a prompt."},{"slug":"how-402-payment-works","title":"How does a 402 payment work?","dek":"Call, challenge, pay, retry, verify."},{"slug":"what-is-a-paid-api","title":"What is a paid API?","dek":"An HTTP interface whose unpaid call is a challenge and whose paid call is the documented result."},{"slug":"what-is-autonomous-procurement","title":"What is autonomous procurement?","dek":"Software that buys inputs under a budget, a rights gate and an audit log — not an unconstrained agent with a credit card."},{"slug":"build-your-first-agent","title":"Build your first agent","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"give-an-agent-tools","title":"Give an agent external tools","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"create-an-mcp-server","title":"Create an MCP server","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"expose-an-api","title":"Expose an API","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"add-machine-readable-schemas","title":"Add machine-readable schemas","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"add-x402-payment-requirements","title":"Add x402 payment requirements","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"create-a-paid-endpoint","title":"Create a paid endpoint","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"give-an-agent-a-wallet-safely","title":"Give an agent a wallet safely","dek":"Delegate spend, never delegate the root key."},{"slug":"discover-paid-services","title":"Discover other paid services","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"buy-transform-sell","title":"Build buy → transform → sell workflows","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"measure-contribution-margin","title":"Measure cost and contribution margin","dek":"Use the calculators. They refuse to forecast."},{"slug":"make-service-discoverable","title":"Make a service machine discoverable","dek":"Same checklist as the Start-here guide, without a marketplace ranking purchase."},{"slug":"agent-to-agent-commerce","title":"Agent-to-agent commerce","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"autonomous-procurement","title":"Autonomous procurement","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"routing-across-providers","title":"Routing across providers","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"payment-orchestration","title":"Payment orchestration","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"reputation","title":"Reputation","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"identity","title":"Identity","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"settlement","title":"Settlement","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"accounting","title":"Accounting","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"evidence-provenance","title":"Evidence and provenance","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"fail-closed-treasury","title":"Fail-closed treasury controls","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"cross-protocol-payments","title":"Cross-protocol payment compatibility","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"marketplaces","title":"Marketplaces","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"agent-discovery","title":"Agent discovery","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"machine-native-business","title":"Machine-native business architecture","dek":"Practical machine-economy lesson. Not a guaranteed-income pitch."},{"slug":"build-your-first-paid-agent-service","title":"Build your first paid agent service","dek":"One route, one schema, one exact price, one 402, one deterministic result."},{"slug":"build-your-first-x402-api","title":"Build your first x402 API","dek":"A competent developer should leave this page with a working unpaid 402 and a deterministic paid handler."},{"slug":"turn-existing-api-into-agent-service","title":"Turn an existing API into an agent-purchasable service","dek":"Keep the function. Freeze the JSON contract. Challenge before side effects."},{"slug":"build-your-first-mcp-tool","title":"Build your first MCP tool","dek":"tools/list describes input schema. tools/call does one job. Payment is an overlay."},{"slug":"make-an-agent-buy-an-api","title":"Make an agent buy an API","dek":"The buyer needs a wallet under a budget, a 402 client, and the schema."},{"slug":"give-an-agent-a-safe-spending-budget","title":"Give an agent a safe spending budget","dek":"Use remainingAtomic, maxPerPurchaseAtomic, allowlisted asset/network, kill switch, idempotency."},{"slug":"buy-add-value-sell","title":"Build a buy → add value → sell workflow","dek":"Pay upstream only when rights allow. Sell the derivative, not the raw passthrough."},{"slug":"make-service-discoverable-by-agents","title":"How to make an API discoverable to agents","dek":"Outcome, schema, price, rail, live 402. Conformance outranks keyword stuffing."},{"slug":"how-to-make-money-with-ai-agents","title":"How to make money with AI agents (without fairy tales)","dek":"Observe demand, sell a derived outcome, measure repeat payers. No guaranteed income."},{"slug":"x402-vs-mpp","title":"x402 vs MPP","dek":"Two HTTP 402 families. Different payloads, facilitators, and settlement stories."},{"slug":"monetize-api-for-agents","title":"Monetize an existing API for agents","dek":"Keep the function. Add a schema, a 402, a price cap, and discovery that matches live behaviour."},{"slug":"how-agents-pay-each-other","title":"How do agents pay each other?","dek":"Discover a contract, receive a 402 or checkout session, settle under a budget, retry, verify."},{"slug":"identify-machine-demand-before-building","title":"How to identify machine demand before building","dek":"Observe payers and repeat use. Listing count is not demand. Comments are signals."},{"slug":"how-to-calculate-marginal-cost","title":"How to calculate marginal cost and contribution","dek":"Price minus variable cost minus failure. Arithmetic, not a forecast."},{"slug":"how-agent-wallets-should-be-controlled","title":"How agent wallets should be controlled safely","dek":"Policy plus arithmetic. The model proposes. Limits decide. Missing config is a stop."}],"helloX402":"/learn/refs/hello-x402"}