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

# Swap across chains

> Send SOL on Solana and receive USDC on Base, choosing the fastest route.

## Prerequisites

* The [TypeScript project](/guides/typescript-setup) plus `npm install @solana/web3.js bs58`.
* A Solana wallet holding SOL, and `SOLANA_PRIVATE_KEY` (base58) and `SOLANA_RPC_URL` in `.env`.

## Script

```typescript src/swap-across-chains.ts theme={null}
import 'dotenv/config';
import { createClient } from '@kernlog/bridg-sdk';
import { Connection, Keypair, VersionedTransaction } from '@solana/web3.js';
import bs58 from 'bs58';

const keypair = Keypair.fromSecretKey(bs58.decode(process.env.SOLANA_PRIVATE_KEY!));
const connection = new Connection(process.env.SOLANA_RPC_URL!);
const bridg = createClient();

async function main() {
  // 1. Quote: 0.5 SOL to USDC on Base
  const quote = await bridg.getQuote({
    fromChain: 'solana',
    toChain: 'base',
    fromToken: null, // null is the chain's native asset
    toToken: 'USDC',
    amountAtomic: '500000000',
    sender: keypair.publicKey.toBase58(),
    recipient: '0xYourBaseWallet',
  });

  // 2. Take the fastest executable row instead of the best-priced one
  const quoteId = quote.bestByTime ?? quote.bestByPrice;
  if (!quoteId) throw new Error('nothing executable');
  const row = quote.quotes.find((q) => q.quoteId === quoteId)!;
  console.log(`${row.venue}: ${row.amountOutAtomic} USDC in ~${row.estimatedSeconds}s`);

  // 3. Build that row
  const build = await bridg.buildTransfer({ decisionId: quote.decisionId, quoteId });

  // 4. Sign the Solana transaction as built. Do not rebuild it: the message bytes are what Bridg verifies.
  const step = build.steps.find((s) => s.step === 'main');
  if (!step || step.vm !== 'svm') throw new Error('expected a Solana main step');
  const tx = VersionedTransaction.deserialize(
    step.encoding === 'base64' ? Buffer.from(step.serializedTx, 'base64') : Buffer.from(step.serializedTx, 'hex'),
  );
  tx.sign([keypair]);
  const signature = await connection.sendRawTransaction(tx.serialize());

  // 5. Report the signature and wait
  await bridg.submitTransfer(build.transferId, { txHash: signature, step: 'main' });
  const transfer = await bridg.waitForTransfer(build.transferId);
  console.log(transfer.status, transfer.receivedAmountAtomic);
}

main().catch((e) => { console.error(e); process.exit(1); });
```

## Notes

* `fromToken: null` or `toToken: null` means the chain's native asset. Symbols and addresses are both accepted.
* A wallet may add its own compute-budget instructions; every instruction Bridg built must stay byte-identical.
* The Solana step carries `refreshBlockhash`; when it is `true`, fetch a fresh blockhash and set it on the message before signing.

## Endpoints used

| SDK               | Endpoint                                                            |
| ----------------- | ------------------------------------------------------------------- |
| `getQuote`        | [`POST /bridge/quote`](/api-reference/quote/quote)                  |
| `buildTransfer`   | [`POST /bridge/build`](/api-reference/quote/build)                  |
| `submitTransfer`  | [`POST /bridge/transfers/{id}/submit`](/api-reference/quote/submit) |
| `waitForTransfer` | [`GET /bridge/transfers/{id}`](/api-reference/quote/transfer)       |