Cross Chain Swaps from Solana

Steps to Cross Chain Swap Tokens from Solana

This guide will walk you through using the /quotes and /status endpoints on 0x’s Cross Chain API to:

1. Fetch a quote
2. Sign and send a transaction
3. Monitor the status of the cross chain swap

In our example, we will be swapping WSOL on Solana to USDC on Base. For understanding how to deal with the native SOL, please refer to Native Tokens Handling.

0. Prerequisites

Make sure you have:

• A funded Solana wallet
• 0x API key
• An RPC Connection (see details below)

import { Connection } from "@solana/web3.js";
// You can replace this with your own or a third-party RPC URL
const connection = new Connection("https://api.mainnet-beta.solana.com");

1. Fetch a Quote

Start by sending a GET request to the 0x /quotes endpoint to get a quotes for a specific tokens and chains pair with selected amount. You may use 'solana' or '999999999991' as the originChain.

const quotesParams = new URLSearchParams({
    originChain: 'solana', // Solana mainnet
    destinationChain: '8453', // Base mainnet
    sellToken: 'So11111111111111111111111111111111111111112', // WSOL on Solana
    buyToken: '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913', // USDC on Base
    sellAmount: '10000000000000000000', // Amount of sellToken in base units
    originAddress: '$USER_TAKER_ADDRESS', // Solana Pubkey that will make the trade
    destinationAddress: '$USER_RECEIVER_ADDRESS', // Base address that will receive the output
    sortQuotesBy: 'price', // Prefer the quote that will result in the best price / output
    maxNumQuotes: 1 // only the best quote
});
const headers = {
    '0x-api-key': '[api-key]', // Get your live API key from the 0x Dashboard (https://dashboard.0x.org/apps)
};
const quoteResponse = await fetch('https://api.0x.org/cross-chain/quotes?' + quotesParams.toString(), { headers });
console.log(await quoteResponse.json());

{
    "liquidityAvailable": true,
    "originChainId": 999999999991,
    "originChain": "solana",
    "destinationChainId": 8453,
    "destinationChain": "base",
    "sellToken": "So11111111111111111111111111111111111111112",
    "buyToken": "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913",
    "issues": {
        "allowance": null,
        "balance": null,
        "simulationIncomplete": false,
        "invalidSwapSourcesPassed": [],
        "invalidBridgesPassed": []
    },
    "zid": "0xbacab00bea6e849844e1be8b",
    "routes": [
        {
            "sellAmount": "10000000000",
            "buyAmount": "1946182873",
            "minBuyAmount": "1926913735",
            "fees": {
                "integratorFee": null,
                "zeroExFee": null,
                "bridgeNativeFee": null
            },
            "gasCosts": {
                "chainType": "svm",
                "base": "5000",
                "priority": "0",
                "total": "5000"
            },
            "steps": [
                {
                    "type": "bridge",
                    "originChainId": 999999999991,
                    "destinationChainId": 8453,
                    "sellToken": "So11111111111111111111111111111111111111112",
                    "buyToken": "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913",
                    "sellAmount": "10000000000",
                    "buyAmount": "1946182873",
                    "minBuyAmount": "1926913735",
                    "provider": "relay",
                    "estimatedTimeSeconds": 3
                }
            ],
            "transaction": {
                "chainType": "svm",
                "details": {
                    "serializedTransaction": "AQAA...JeZQ=="
                }
            },
            "estimatedTimeSeconds": 3,
            "issues": {
                "allowance": null,
                "balance": null,
                "simulationIncomplete": false
            }
        }
    ]
}

2. Sign and submit transaction

In the next step, you need to build VersionedTransaction based on returned transaction data, sign it with your wallet, and send it to the Solana network, and wait for transaction confirmation.

const serializedTx = quotesResponse.quotes[0].transaction.details.serializedTransaction;
const transactionBuffer = Buffer.from(serializedTx, "base64");
const transaction = VersionedTransaction.deserialize(transactionBuffer);
transaction.sign([keypair]);
const signature = await connection.sendTransaction(transaction, {
    skipPreflight: false, // Let Solana do final preflight
    preflightCommitment: "confirmed",
});
const confirmation = await connection.confirmTransaction(
    {
      signature,
      ...(await connection.getLatestBlockhash()),
    },
    "finalized",
);

3. Monitor the cross chain execution

The last step is to monitor the execution of the cross chain transaction, including the fill on the destination chain. For that, we will use the /status endpoint.

const statusParams = new URLSearchParams({
    originChain: "solana", // origin chain
    originTxHash: signature, // transaction hash of the origin chain transaction, submitted in previous step
});
const headers = {
    '0x-api-key': '[api-key]', // Get your live API key from the 0x Dashboard (https://dashboard.0x.org/apps)
};
const statusResponse = await fetch('https://api.0x.org/cross-chain/status?' + statusParams.toString(), { headers });
console.log(await statusResponse.json());

In your application, you might need to monitor the status repeatedly, as bridging operation might take several seconds or minutes to complete.

{
    "status": "bridge_filled",
    "bridge": "relay",
    "transactions": [
        {
            "chainId": 999999999991,
            "chain": "solana",
            "txHash": "5UnA6U8LBcV7ZrBcq9ZVJrAmp86f9m5yQyRtBF3nFYYFmQAjknBNiYGvj41CAUf9ZqAUfqYVME571KskA7ERX2ep",
            "timestamp": 1755200803
        },
        {
            "chainId": 8453,
            "chain": "base",
            "txHash": "0xbc52c14a42fe35cdf6f2eef0676bfa9af51870a72f19e9f510ea1e31619a6b7d",
            "timestamp": 1755200808
        }
    ],
    "zid": "0x9562c9b7dd462114505f5dcd"
}

Solana transaction v1

Solana is rolling out transaction format v1.

The Cross-Chain API will keep returning v0 whenever possible, so existing integrations continue to work. In some cases, the returned transaction may use v1. This can happen when a bridge provider gives us a v1 transaction or when the transaction is too large for v0.

serializedTransaction remains base64 encoded for both versions. Make sure your client can deserialize, sign, and send v1 before submitting the transaction.

If your app calls getTransaction after submission, pass maxSupportedTransactionVersion: 1 as the JSON integer 1. If you track the swap through the 0x /status endpoint, you do not need to make this RPC call yourself.

Extra - using alternative gas payer

One thing that is specific to cross chain swaps originating from Solana is the ability to specify an alternative wallet as a gas payer. When requesting a /quote, you need to pass an extra gasPayer parameter, equal to base58-encoded pubkey of the gas payer. Then, when processing the response, you need to additionally sign the transaction with the gas payer wallet.

const serializedTx = quote.transaction.details.serializedTransaction;
const transactionBuffer = Buffer.from(serializedTx, "base64");
const transaction = VersionedTransaction.deserialize(transactionBuffer);
// Sign transaction with both keypairs
console.log("Signing transaction with gas payer and user keypairs...");
transaction.sign([gasPayerKeypair, keypair]);

In the examples repo, you can find a dedicated end-to-end example utilising a gas payer functionality.

Extra - routes requiring an ephemeral signer (Circle CCTP)

Some Solana-origin routes need an extra one-shot transaction signer in addition to your wallet. Currently this applies to Circle CCTP, where the burn instruction creates a fresh on-chain account (message_sent_event_data) that must co-sign the transaction.

These routes are opt-in: they are only included in your quotes when you pass the solanaEphemeralSignerPubkey parameter. To use them:

1. Generate a fresh keypair for every quote request and pass its base58-encoded pubkey as solanaEphemeralSignerPubkey.
2. Sign the returned transaction with both your wallet and the ephemeral keypair.

import { Keypair } from "@solana/web3.js";
// 1. Fresh keypair per quote request
const ephemeralSigner = Keypair.generate();
const quotesParams = new URLSearchParams({
    // ... the parameters from step 1 ...
    solanaEphemeralSignerPubkey: ephemeralSigner.publicKey.toBase58(),
});
// 2. Sign with both keypairs before sending
const transaction = VersionedTransaction.deserialize(
    Buffer.from(quote.transaction.details.serializedTransaction, "base64"),
);
transaction.sign([keypair, ephemeralSigner]);

A few things to keep in mind:

• The account must not already exist on-chain, so never reuse a keypair across requests.
• The keypair is not reusable after the transfer - the program takes ownership of the account. You can discard the secret key once the transaction is confirmed.
• Creating the account requires a small rent deposit in SOL, paid by the fee payer and included in the quote’s gasCosts.