> For the complete documentation index, see [llms.txt](https://docs.abapays.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.abapays.com/protocols/x402.md).

# x402

> Zero setup

An independent agent — say, an FX agent holding a Celo wallet — never needs to know AbaPay exists in advance. The whole exchange happens over plain HTTP, challenge and response.

## The flow

1. Holds or uses a Celo wallet.
2. Calls AbaPay's quote / pay\_bill endpoint directly.
3. Gets `402 Payment Required` back, with the exact price and asset.
4. Signs an EIP-3009 `transferWithAuthorization` with that same wallet — nothing else.
5. Retries the request with the signed authorization attached.
6. AbaPay settles on Celo via Celo's own x402 facilitator and vends the bill.

> **Never required for this path:** abapays.com account, Agent Hub, API key, PIN, wallet-signature link.

## Request & response

`POST /api/pay/x402` — no `X-PAYMENT` header yet:

```json
{
  "serviceID": "mtn", "serviceCategory": "AIRTIME",
  "network": "MTN", "billersCode": "08012345678",
  "nairaAmount": 1000, "token": "USDT",
  "blockchain": "CELO", "wallet_address": "0xYourAgentWallet..."
}
```

← `402 Payment Required` (real field names):

```json
{
  "x402Version": 1,
  "error": "Payment required",
  "accepts": [{
    "scheme": "exact",
    "network": "eip155:42220",
    "asset": "0x48065fbBE25f71C9282ddf5e1cD6D6A887483D5e",
    "payTo": "0x5df8aE2B963165b735B18Ca86B1ea448d2AA032C",
    "maxTimeoutSeconds": 86400,
    "extra": { "name": "Tether USD", "version": "1", "primaryType": "TransferWithAuthorization" }
  }]
}
```

`POST /api/pay/x402` with `X-PAYMENT: <base64 signed authorization>` → `200 OK`:

```json
{
  "success": true, "status": "SUCCESS",
  "tx_hash": "0x91a3...4f2c", "request_id": "req_...",
  "purchased_code": null, "units": null
}
```

Both USDC and USD₮ settle via Celo's own x402 facilitator — each implements EIP-3009. Full field reference: [openapi.json](https://abapays.com/openapi.json).

## Don't hand-roll the signing

`abapay-sdk`'s `payBillViaX402()` does exactly the three requests and one signature above — pass it a viem account and the bill details, get back the settlement result. See [the SDK chapter](/build/sdk.md).


---

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