Handling Transfer Actions

Learn how to execute transfer transactions on different blockchains after creating a swap via the Layerswap API.

Overview

When you create a swap via POST /api/v2/swaps, the response includes a deposit_actions array. Each transfer action contains the destination address, amount, and a blockchain-specific call_data payload — everything you need to construct and submit a transaction on the source chain. After broadcasting the transaction, you notify Layerswap with the transaction hash via the speedup endpoint so it can match the deposit and complete the swap.

Transfer Action Schema

Each item in the deposit_actions array has the following structure:

type · string

Either transfer (wallet transaction) or manual_transfer (manual deposit to an address). Use the action with type: "transfer" for programmatic transfers.

to_address · string

The deposit address to send funds to.

amount · number

The amount to transfer in human-readable units (e.g. 0.1 ETH, not wei).

amount_in_base_units · string

The amount in the token’s smallest unit (e.g. wei for ETH, satoshi for BTC).

call_data · string

Blockchain-specific payload used to construct the transaction. The format varies by chain — see the chain-specific guides below.

network · object

The source network object, including name, type, chain_id, and node_url.

token · object

The token being transferred, including symbol, decimals, and contract (null for native tokens).

fee_token · object

The token used to pay transaction fees on this network.

order · number

Execution order if there are multiple transfer actions.

Step-by-Step Flow

1. Create a Swap

   Call POST /api/v2/swaps with use_deposit_address: false and include the source_address parameter. The response will contain deposit_actions.

   Starknet, Paradex, and TON only support the transfer flow — use_deposit_address: true is rejected for these networks. All other source networks accept either mode.

   curl -X POST https://api.layerswap.io/api/v2/swaps \
     -H "X-LS-APIKEY: your_api_key" \
     -H "Content-Type: application/json" \
     -d '{
       "source_network": "ETHEREUM_MAINNET",
       "source_token": "ETH",
       "destination_network": "ARBITRUM_MAINNET",
       "destination_token": "ETH",
       "destination_address": "0xRecipient...",
       "source_address": "0xSender...",
       "amount": "0.1",
       "use_deposit_address": false
     }'
   
2. Extract the Transfer Action

   From the response, find the transfer action with type: "transfer":

   const response = await createSwap(/* ... */);
   const depositAction = response.deposit_actions.find(
     action => action.type === "transfer"
   );
   
   const { call_data, to_address, amount, network, token } = depositAction;
   
3. Execute the Transaction

   Use the call_data, to_address, and amount to construct and send a blockchain-specific transaction. See the chain guides below for implementation details.

4. Notify Layerswap

   After the transaction is submitted, call the speedup endpoint so Layerswap can match it 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": "0xYourTransactionHash..." }'
   
5. Monitor Status

   Poll GET /api/v2/swaps/{swap_id} or use webhooks to track the swap through its lifecycle.

call_data Format by Chain

The call_data field is the key piece — its format depends on the source blockchain:

Blockchain	call_data Format	Guide
EVM (Ethereum, Arbitrum, Base, etc.)	Hex-encoded transaction data (0x...)	EVM Guide
Bitcoin	Numeric memo (encoded as OP_RETURN)	Bitcoin Guide
Solana	Base64-encoded serialized transaction	Solana Guide
Starknet	JSON array of Starknet calls	Starknet Guide
TON	JSON object with comment (and amount for Jettons)	TON Guide
Tron	String memo (hex-encoded into transaction data)	Tron Guide
Fuel	JSON object with script and quantities	Fuel Guide