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Overview

Starknet deposits are simple to execute because the Layerswap API returns a pre-built array of Starknet calls in call_data. You parse the JSON and pass it directly to the account’s execute method, which handles multicall execution natively. Prerequisites:
  • starknet.js for account interaction and transaction execution
Supported networks: Starknet Mainnet, Starknet Sepolia

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call_data Format

For Starknet, call_data is a JSON-encoded array of call objects. Each call in the array specifies a contract invocation: 
[
  {
    "contractAddress": "0x049d36570d4e46f48e99674bd3fcc84644ddd6b96f7c741b1562b82f9e004dc7",
    "entrypoint": "transfer",
    "calldata": ["0xRecipient", "0xAmountLow", "0xAmountHigh"]
  }
]
For ERC-20 token transfers, the array typically contains a single transfer or approve + transfer call. For native ETH on Starknet, it’s a direct transfer call on the ETH contract.

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Transaction Construction

1

Parse call_data

Deserialize the JSON string into an array of Starknet call objects.
2

Execute via Account

Pass the calls array to account.execute(). Starknet natively supports multicall, so all calls in the array are executed atomically in a single transaction.
3

Return the transaction hash

The execute method returns an object with transaction_hash.

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Full Example (Server-side with Private Key)

import { Account, RpcProvider, Call } from "starknet";

async function executeStarknetDeposit(
  depositAction: any,
  senderAddress: string,
  privateKey: string
) {
  const { call_data, network } = depositAction;

  const provider = new RpcProvider({ nodeUrl: network.node_url });
  const account = new Account(provider, senderAddress, privateKey);

  // Parse the call_data JSON into Starknet calls
  const calls: Call[] = JSON.parse(call_data);

  // Execute the multicall transaction
  const { transaction_hash } = await account.execute(calls);

  if (!transaction_hash) {
    throw new Error("No transaction hash returned");
  }

  // Optionally wait for confirmation
  await provider.waitForTransaction(transaction_hash);

  return transaction_hash;
}

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Full Example (Browser with starknet.js + Wallet)

When using a browser wallet like ArgentX or Braavos, the wallet injects a starknet object. Use get-starknet to connect: 
import { connect } from "get-starknet";
import { Call } from "starknet";

async function executeStarknetDeposit(depositAction: any) {
  const { call_data } = depositAction;

  // Connect to wallet
  const starknet = await connect();
  if (!starknet?.isConnected || !starknet.account) {
    throw new Error("Starknet wallet not connected");
  }

  // Parse the call_data JSON
  const calls: Call[] = JSON.parse(call_data);

  // Execute through the connected wallet
  const { transaction_hash } = await starknet.account.execute(calls);

  if (!transaction_hash) {
    throw new Error("No transaction hash returned");
  }

  return transaction_hash;
}

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Full Example (Using starknet-react hooks)

If you use starknet-react, you can access the account from the hook: 
import { useAccount } from "@starknet-react/core";
import { Call } from "starknet";

function useStarknetDeposit() {
  const { account } = useAccount();

  async function executeDeposit(depositAction: any): Promise<string> {
    if (!account) {
      throw new Error("Starknet account not connected");
    }

    const calls: Call[] = JSON.parse(depositAction.call_data);
    const { transaction_hash } = await account.execute(calls);

    if (!transaction_hash) {
      throw new Error("No transaction hash returned");
    }

    return transaction_hash;
  }

  return { executeDeposit };
}

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Next Step

After the transaction is submitted, notify Layerswap so it can match your deposit faster: 
curl -X POST https://api.layerswap.io/api/v2/swaps/{swap_id}/deposit_speedup \
  -H "X-LS-APIKEY: your_api_key" \
  -H "Content-Type: application/json" \
  -d '{ "transaction_id": "YOUR_TX_HASH" }'
See the full deposit flow for details.