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

# Quickstart

Buying a token, end to end. Node 22 or newer.

```sh
npm add @surged/sdk viem
```

```ts
import { createWalletClient, createPublicClient, http, type Address } from 'viem'
import { privateKeyToAccount } from 'viem/accounts'
import {
  arc,
  curveStateFromApi,
  encodeBuy,
  minOutWithSlippage,
  previewBuy,
} from '@surged/sdk'

const API = 'https://api.surged.fun'
const token = '0xA65DE690ea02Ec5e2D8071c7943B4a34AD6B026c' as Address

// 1. Read the curve and the head of the chain.
const launch = await fetch(`${API}/launches/${token}`).then((r) => r.json())
const { head } = await fetch(`${API}/health`).then((r) => r.json())

// 2. Price the buy. It lands in the next block, which is what the snipe tax is measured against.
const quoteIn = 10n * 10n ** 18n // 10 USDC
const quote = previewBuy(curveStateFromApi(launch), quoteIn, {
  currentBlock: BigInt(head) + 1n,
})
console.log('tokens out', quote.tokensOut, 'snipe tax', quote.snipeTax)

// 3. Send it. `minTokensOut` is what protects you if the price moves first.
const account = privateKeyToAccount(process.env.PRIVATE_KEY as `0x${string}`)
const chain = { ...arc, rpcUrls: { default: { http: ['https://rpc.mainnet.arc.io'] } } }
const wallet = createWalletClient({ account, chain, transport: http() })
const publicClient = createPublicClient({ chain, transport: http() })

const call = encodeBuy({
  pairToken: launch.pairToken,
  quoteIn,
  minTokensOut: minOutWithSlippage(quote.tokensOut, 500), // 5%
  recipient: account.address,
})
const hash = await wallet.sendTransaction({ to: launch.curve, ...call })
const receipt = await publicClient.waitForTransactionReceipt({ hash })
console.log(receipt.status)
```

## What to watch

**`quote.crossing`** is `true` when your buy takes the last tokens on the curve and triggers graduation. The curve only sells what is left and refunds the difference, which `quote.refund` tells you in advance.

**`quote.snipeTax`** is the anti-snipe charge, which is severe in the first blocks of a launch: it starts at 99% and reaches zero six blocks later, about three seconds. It is not a bug; see [Fees and the snipe tax](/integration/fees.md).

**Gas comes out of the same balance you are spending.** USDC is the native coin of Arc, so a buy sized at your full balance cannot pay for itself. Keep a reserve; the frontend holds back the worst-case gas at the current base fee, which on a busy day is far above the 20 gwei floor.

## Selling

Selling needs an approval first, because the curve pulls the tokens from you.

```ts
import { encodeSell, launcherTokenAbi, previewSell } from '@surged/sdk'
import { encodeFunctionData } from 'viem'

const quote = previewSell(curveStateFromApi(launch), tokensIn)

await wallet.sendTransaction({
  to: launch.token,
  data: encodeFunctionData({
    abi: launcherTokenAbi,
    functionName: 'approve',
    args: [launch.curve, tokensIn],
  }),
})
await wallet.sendTransaction({
  to: launch.curve,
  ...encodeSell({
    tokensIn,
    minQuoteOut: minOutWithSlippage(quote.quoteOut, 500),
    recipient: account.address,
  }),
})
```

Once a token has graduated its curve stops trading. `launch.phase` tells you: while it is `curve` you trade here, and once it is `pool` you trade on Uniswap. See [Graduation](/integration/graduation.md).


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