# Neuronto Payments

> An x402 payment facilitator: it verifies signed stablecoin payments and settles them on-chain, so any API, MCP tool or agent can charge per request, and any agent can pay for one, with a wallet and no account. Operated by Neuronto (https://neuronto.com).

## When to use it

- **Charging for an API, MCP tool or agent service per request.** Put x402 middleware in front of a route and point its facilitator at `https://pay.neuronto.com`. You are paid in USDC per call; your buyers need no signup. Start at https://pay.neuronto.com/developers#accept-payments.
- **Paying for a resource that answered HTTP 402.** Use an x402 client; it reads the terms, signs, retries.
- **Checking which networks are live** before advertising terms: `GET https://pay.neuronto.com/supported`. A network whose settlement cannot be paid for is withdrawn from that list before anything else changes.
- **Finding services an agent can buy right now:** `GET https://pay.neuronto.com/discovery/resources`, the catalogue of every resource that has actually been paid for through this facilitator.

Do not use it for card payments, fiat payouts, bank transfers, custody of funds or subscription billing. It never holds anyone's balance: a settlement moves funds from the payer's wallet straight to the address the merchant advertised; the facilitator only broadcasts the payer's own signed authorisation and pays the network fee.

## How an agent calls it

1. `GET https://pay.neuronto.com/supported` to pick a live network and scheme.
2. `POST https://pay.neuronto.com/verify` with `{"x402Version": 2, "paymentPayload": ..., "paymentRequirements": ...}` to check a signed payment. Free, moves nothing.
3. `POST https://pay.neuronto.com/settle` with the same body to move the funds. Idempotent: the identical body is settled once, and re-submitting it returns the recorded outcome.
4. Errors are always JSON. `/verify` answers `{"isValid": false, "invalidReason": ..., "invalidMessage": ...}`; `/settle` answers `{"success": false, "errorReason": ..., "errorMessage": ..., "transaction": ..., "network": ..., "payer": ...}`. Every other path answers RFC 9457 `application/problem+json`. Treat `errorReason: "settlement_pending"` as unresolved, not failed: re-submit the identical body to poll.

No API key. No account. Versioned by the `x402Version` field in the body, not by a URL prefix.

## Networks

| Network | CAIP-2 | v1 name | Asset | Testnet |
|---|---|---|---|---|
| Base Sepolia | `eip155:84532` | `base-sepolia` | USDC `0x036CbD53842c5426634e7929541eC2318f3dCF7e` | yes |
| Base | `eip155:8453` | `base` | USDC `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913` | no |

## Surfaces

- [Developer reference](https://pay.neuronto.com/developers), also as Markdown at https://pay.neuronto.com/developers.md
- [OpenAPI 3.1](https://pay.neuronto.com/openapi.json)
- [Pricing](https://pay.neuronto.com/pricing), Markdown at https://pay.neuronto.com/pricing.md
- [About](https://pay.neuronto.com/about)
- [ARD manifest](https://pay.neuronto.com/.well-known/ard.json), Agentic Resource Discovery entries for this API
- `GET /supported`, `GET /discovery/resources`, `GET /discovery/stats`, `GET /health`

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