Neuronto Payments: guides
Long-form answers to the questions people actually ask about paying for APIs, tools and agent services over HTTP. Every figure on these pages is either measured here or cited to the source it came from.
What is x402? The HTTP status code that lets software pay for things
x402 is an open payment protocol built on HTTP 402 Payment Required: the server answers an unpaid request with machine-readable terms, the client signs a stablecoin transfer, and retries. What it does, what it does not do, and how a facilitator fits.
How to charge per API request, and what an API call actually costs
An API call costs two very different things, and mixing them up is where most API pricing goes wrong. Serving an ordinary request costs the provider a small fraction of a cent. Cloudflare Workers bills $0.30 per additional million requests past the 10 million included each month on its Standard plan
How to charge for an MCP server or tool
An MCP server charges for a tool by answering the tool call with a price instead of a result. The agent sends tools/call, the server replies with a tool result carrying isError: true and a PaymentRequired object listing what it accepts, the agent signs a stablecoin payment and repeats the identical
Building and testing an x402 integration, end to end
x402 turns a status code that HTTP reserved and never used into a payment handshake. RFC 9110 still says, in section 15.5.3, that "The 402 Payment Required status code is reserved for future use." The x402 documentation describes what it now carries: it "is built around the HTTP 402 Payment Required
Giving an AI agent a wallet, and keeping it inside a limit
An AI agent wallet is an ordinary crypto account whose private key happens to sit inside a program rather than in a person's pocket, and the moment you fund it, the agent can spend it. The only spending limit that survives a bad day is one enforced somewhere the agent cannot reach: the balance of th
What an x402 facilitator does, and how to choose one
An x402 facilitator verifies a signed stablecoin payment and submits it on chain, holding no funds at any point. What /verify and /settle actually do, a twelve point selection checklist, when self hosting wins, and when you do not need a facilitator at all.
The agent payment standards, counted: x402, AP2, ACK and what is actually implemented
A count of 326 agent-related IETF internet-drafts and the implementing repositories behind each named agent payment standard. MCP at 168, AP2 at 63, x402 at 27, with a median of one implementation per draft. Method, limits and every raw number.
Signed offers and receipts in x402: what they prove, and the three details implementations get wrong
The x402 Offer and Receipt extension adds server-side signatures to a paid HTTP call: a signed offer commits the server to its quoted terms, and a signed receipt states that payment arrived and the service was delivered. The EIP-712 chainId is the constant 1, the canonical types are never transmitte
How to test an x402 implementation, and what a conformance vector actually proves
An x402 implementation can pass every test it owns and still fail to interoperate, because its code and its tests share one wrong assumption. Conformance vectors break that symmetry. Covers the five layers worth testing apart, the EIP-712 signing traps, a set of 13 published vectors, and why /verify