# Try Radius

*Create a wallet, send SBC, and pay for an API request*

Everything on this page runs on Radius Testnet with test funds. Each step calls the same `radius-sdk` functions you use in your own code, and links every transaction to the testnet explorer.

## 1. Create and fund a wallet

Create a wallet, then click **Get testnet SBC**. The faucet sends 0.5 SBC, the payment asset, and a small amount of RUSD, the native fee asset.

Create and fund a testnet wallet with radius-sdk:

```javascript
import { createRadiusFetch } from 'radius-sdk/client';
import { generatePrivateKey } from 'viem/accounts';

const payFetch = createRadiusFetch({ network: 'testnet', signer: generatePrivateKey(), maxPerRequest: '0.01 SBC' });
console.log('wallet', payFetch.address);
console.log(await payFetch.fund()); // 0.5 SBC and 0.001 RUSD from the testnet faucet
console.log(await payFetch.balances());
```

The private key is generated in your browser and stays in its local storage. The other examples in these docs use the same wallet. In your own code, `createRadiusFetch` takes the key as `signer`, and `fund()` calls the [testnet faucet](/build/wallet.md).

## 2. Send SBC

Send SBC to any address. The default recipient is the testnet faucet, so the test funds go back to it.

Send SBC from a funded testnet wallet with radius-sdk:

```javascript
import { createRadiusFetch } from 'radius-sdk/client';

const payFetch = createRadiusFetch({ network: 'testnet', signer: process.env.RADIUS_PRIVATE_KEY, maxPerRequest: '0.01 SBC' });
const tx = await payFetch.send('0xRecipientAddress', '0.01 SBC'); // waits for the receipt
console.log(tx.status, tx.explorerUrl);
```

The time includes signing, sending, and waiting for the transaction receipt: Radius confirms transactions with sub-second finality. The fee is a fixed gas price paid in RUSD. A wallet that holds only SBC can still send, because the [Turnstile](/reference/fees.md#turnstile) converts SBC to RUSD when a transaction needs gas.

## 3. Pay for an API request

Request a “Hello, world!” message for 0.001 SBC. The greeting is the resource you pay to receive; x402 handles the payment. Test funds go back to the testnet faucet.

1. Click **Request without paying**. The API answers `402 Payment Required` and describes the price in the `PAYMENT-REQUIRED` header.
2. Click **Pay and request**. The client reads the offer, checks it against your limit, signs a payment authorization, and sends the request again. The API settles the payment and returns `{"message":"Hello, world!"}`.
3. Lower **Your limit per request** to **0.0001 SBC** and click **Pay and request** again. The price exceeds your limit, so the client refuses before signing a payment.

Pay for an x402 endpoint within a per-request limit with radius-sdk:

```javascript
import { createRadiusFetch, getPaymentReceipt } from 'radius-sdk/client';

const payFetch = createRadiusFetch({ network: 'testnet', signer: process.env.RADIUS_PRIVATE_KEY, maxPerRequest: '0.01 SBC' });
const res = await payFetch('https://docs.radiustech.xyz/api/try/hello'); // 0.001 SBC
console.log(res.status, await res.json(), getPaymentReceipt(res, payFetch.network));
// Set maxPerRequest to '0.0001 SBC' to see the client refuse before signing (price_above_limit).
```

A new wallet needs only testnet SBC to pay. The SDK signs the payment authorization, and the Radius facilitator submits the settlement transaction. See [x402 payments](/build/x402.md) for the full request lifecycle.

## Build it yourself

* [Accept payments](/build/accept-payments.md): charge for API routes in a Hono app or Cloudflare Worker.
* [Make payments](/build/make-payments.md): pay x402 endpoints from an app or agent, within a limit.
* [Sell a data lookup](/build/tutorials/sell-data.md) and [buy a data lookup](/build/tutorials/buy-data.md): build a more detailed paid API example on testnet.
* [radius-sdk reference](/reference/radius-sdk.md): every option and function used on this page.