> For the complete documentation index, see [llms.txt](https://unibaseio.gitbook.io/unibase-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://unibaseio.gitbook.io/unibase-docs/get-started/pay-quickstart.md).

# Unibase Pay Quick Start

Use the x402 API to verify and settle payments in 5 minutes.

### 1. API Base URL

```
https://api.x402.unibase.com/v2
```

### 2. Supported Networks

| Network         | CAIP-2         |
| --------------- | -------------- |
| BNB Smart Chain | `eip155:56`    |
| BSC Testnet     | `eip155:97`    |
| Base            | `eip155:8453`  |
| Base Sepolia    | `eip155:84532` |
| Polygon         | `eip155:137`   |
| Arbitrum One    | `eip155:42161` |

### 3. First call

`GET /supported` needs no auth and no payload, so it is both the liveness check and the source of truth for what the facilitator accepts. There is no `/health` endpoint.

```bash
curl https://api.x402.unibase.com/v2/supported
```

### 4. Endpoints

| Method | Endpoint     | Description                                 |
| ------ | ------------ | ------------------------------------------- |
| POST   | `/verify`    | Check a payment payload without settling it |
| POST   | `/settle`    | Settle a payment on-chain                   |
| GET    | `/supported` | Scheme and network pairs served             |

`/verify` and `/settle` are POST only — a GET returns 405.

### 5. Payment Schemes

* `exact` — fixed, known amount
* `upto` — authorize a ceiling, settle actual usage (metered billing)
* `batch-settlement` — many micropayments in one on-chain transaction

### 6. Protocol Reference

See [x402.org](https://x402.org) for the full protocol specification. Servers declare payment requirements; clients send signed payloads; facilitators verify and settle on-chain.

***

### Next Steps

* [API Reference](/unibase-docs/unibase-pay/api-reference.md)
* [Privy Wallet](/unibase-docs/unibase-pay/privy-wallet.md) — Agent custodial wallet via MCP/Skill