> ## Documentation Index
> Fetch the complete documentation index at: https://stablelabs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# SDK quickstart

> Install the Stable SDK, send your first USDT0 transfer on testnet, and preview a bridge and swap quote.

You'll install `@stablechain/sdk`, create a client signed by a private key, send a USDT0 transfer on Stable Testnet, and fetch a bridge and swap quote. Total time: about five minutes.

<Note>
  Stable uses USDT0 as the gas token. You only need testnet USDT0 to transact — there's no separate native asset to fund.
</Note>

## Prerequisites

* Node.js 20 or later
* A test private key with testnet USDT0. See [Fund your testnet wallet](/en/how-to/use-faucet).

## 1. Install

```bash theme={"dark"}
mkdir stable-sdk-quickstart && cd stable-sdk-quickstart
npm init -y && npm install @stablechain/sdk viem
```

```text theme={"dark"}
added 2 packages, audited 3 packages in 2s
```

Save your test key:

```bash theme={"dark"}
echo "PRIVATE_KEY=0xYOUR_TEST_KEY" > .env
```

## 2. Create a client

Create `index.ts`:

```ts theme={"dark"}
import "dotenv/config";
import { createStable, Network } from "@stablechain/sdk";
import { privateKeyToAccount } from "viem/accounts";

const account = privateKeyToAccount(process.env.PRIVATE_KEY as `0x${string}`);

const stable = createStable({
  network: Network.Testnet,
  account,
});

console.log("Signer:", account.address);
```

```text theme={"dark"}
Signer: 0xYourAddress
```

`createStable` accepts three signing modes: `account` (server-side, shown above), `transport` (browser wallet via `custom(window.ethereum)`), or `walletClient` (a pre-built viem `WalletClient`). See [Use the SDK with viem](/en/how-to/sdk-with-viem) for all three.

## 3. Send a USDT0 transfer

Append to `index.ts`:

```ts theme={"dark"}
const { txHash } = await stable.transfer({
  from: account.address,
  to: "0x000000000000000000000000000000000000dEaD",
  amount: 0.001,
});

console.log("Transfer:", txHash);
```

Run it:

```bash theme={"dark"}
npx tsx index.ts
```

```text theme={"dark"}
Signer: 0xYourAddress
Transfer: 0x8f3a...2d41
```

Open the hash on the [testnet explorer](https://testnet.stablescan.xyz) to confirm.

## 4. Quote a bridge

Bridge USDT0 from Ethereum Sepolia to Stable Testnet. `quoteBridge` is a read-only call — no signature, no gas:

```ts theme={"dark"}
import { Chain } from "@stablechain/sdk";

const bridgeQuote = await stable.quoteBridge({
  fromChain: Chain.Sepolia,
  toChain: Chain.StableTestnet,
  fromToken: "0xc4DCC311c028e341fd8602D8eB89c5de94625927",
  toToken: "0x78Cf24370174180738C5B8E352B6D14c83a6c9A9",
  amount: 1,
});

console.log("Bridge quote:", bridgeQuote);
```

```text theme={"dark"}
Bridge quote: { toAmount: 0.999812 }
```

Pass the quote into `stable.bridge({ ...params, quote })` to execute. The SDK picks LayerZero for USDT0 → USDT0 routes and LI.FI for everything else.

## 5. Quote a swap

Swaps run on Stable through LI.FI. The quote returns the expected output and a pre-built transaction:

```ts theme={"dark"}
const swapQuote = await stable.quoteSwap({
  fromToken: "0x8a2B28364102Bea189D99A475C494330Ef2bDD0B",
  toToken: "0x78Cf24370174180738C5B8E352B6D14c83a6c9A9",
  amount: 1,
  fromDecimals: 6,
});

console.log("You'll receive:", swapQuote.toAmount, "USDT0");
```

```text theme={"dark"}
You'll receive: 0.998 USDT0
```

Call `stable.swap({ ...params, quote: swapQuote })` to execute. Approval for ERC-20 sources is handled internally.

## Next recommended

<CardGroup cols={3}>
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    Every parameter, return type, and error class.
  </Card>

  <Card title="Use with viem" icon="code" href="/en/how-to/sdk-with-viem">
    Switch between private-key, browser-wallet, and pre-built `WalletClient` signing.
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  <Card title="Use with wagmi" icon="atom" href="/en/how-to/sdk-with-wagmi">
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