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Overview

TON deposits require constructing a TON-specific message payload. The flow differs depending on whether you’re transferring native TON or a Jetton (TRC-20-like token on TON). The call_data from the Layerswap API contains the information needed to build the correct payload. Prerequisites:

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call_data Format

For TON, call_data is a JSON string containing: 
{
  "amount": "1000000000",
  "asset": "TON",
  "comment": "layerswap_memo_identifier"
}
  • comment — A text memo that Layerswap uses to identify the deposit. This is embedded in the transaction payload.
  • amount — The transfer amount in base units (nanotons for TON, base units of the Jetton otherwise). Always present; for native TON it matches the transfer action’s amount field.
  • asset — The source asset symbol (e.g. TON, USDT). Informational; the actual contract is on the transfer action’s token.contract.

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Native TON Transfer

For native TON transfers (when token.contract is null), the transaction is a simple message to the deposit address with a comment payload.

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Transaction Construction

1

Parse call_data

Extract the comment field from the JSON.
2

Build the comment cell

Create a TON cell with a 32-bit zero prefix (indicates a text comment) followed by the comment string.
3

Construct the message

Send a message to to_address with the deposit amount (converted to nanotons) and the comment cell as payload.

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Full Example

import { beginCell, toNano } from "@ton/ton";

function buildNativeTonTransaction(
  depositAction: any
) {
  const { call_data, to_address, amount } = depositAction;
  const { comment } = JSON.parse(call_data);

  const body = beginCell()
    .storeUint(0, 32)           // 0 opcode = text comment
    .storeStringTail(comment)
    .endCell();

  return {
    validUntil: Math.floor(Date.now() / 1000) + 360,
    messages: [
      {
        address: to_address,
        amount: toNano(amount).toString(),
        payload: body.toBoc().toString("base64"),
      },
    ],
  };
}

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Jetton Transfer

For Jetton transfers (when token.contract is not null), you need to build a Jetton transfer message that targets the sender’s Jetton wallet address (not the Jetton master contract).

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Transaction Construction

1

Parse call_data

Extract both comment and amount from the JSON.
2

Resolve the sender's Jetton wallet

Use the Jetton master contract to look up the sender’s Jetton wallet address via get_wallet_address.
3

Build the Jetton transfer cell

Construct a cell with the Jetton transfer opcode (0x0f8a7ea5), the Jetton amount, the destination address, and a forward payload containing the comment.
4

Send the message

Send the message to the sender’s Jetton wallet address with enough TON attached to cover fees.

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Full Example

import {
  Address,
  JettonMaster,
  TonClient,
  beginCell,
  toNano,
} from "@ton/ton";

async function buildJettonTransaction(
  depositAction: any,
  senderAddress: string,
  tonClient: TonClient
) {
  const { call_data, to_address, token } = depositAction;
  const { comment, amount: jettonAmount } = JSON.parse(call_data);

  const destinationAddress = Address.parse(to_address);
  const userAddress = Address.parse(senderAddress);

  // Build the forward payload (comment)
  const forwardPayload = beginCell()
    .storeUint(0, 32)
    .storeStringTail(comment)
    .endCell();

  // Build the Jetton transfer body
  const body = beginCell()
    .storeUint(0x0f8a7ea5, 32)         // Jetton transfer opcode
    .storeUint(0, 64)                   // query_id
    .storeCoins(BigInt(jettonAmount))   // Jetton amount in base units
    .storeAddress(destinationAddress)   // destination
    .storeAddress(destinationAddress)   // response excess destination
    .storeBit(0)                        // no custom payload
    .storeCoins(toNano("0.00002"))      // forward amount for notification
    .storeBit(1)                        // forward payload as reference
    .storeRef(forwardPayload)
    .endCell();

  // Resolve the sender's Jetton wallet address
  const jettonMasterAddress = Address.parse(token.contract);
  const jettonMaster = tonClient.open(
    JettonMaster.create(jettonMasterAddress)
  );
  const jettonWalletAddress =
    await jettonMaster.getWalletAddress(userAddress);

  return {
    validUntil: Math.floor(Date.now() / 1000) + 360,
    messages: [
      {
        address: jettonWalletAddress.toString(),
        amount: toNano("0.045").toString(), // TON for fees; excess is returned
        payload: body.toBoc().toString("base64"),
      },
    ],
  };
}

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Sending the Transaction

The TON Connect tab is for browser wallets like Tonkeeper or MyTonWallet — it picks between the native and Jetton builders above based on token.contract. The Server-side tab signs and sends directly with a wallet key for backend use. 
import { TonConnectUI } from "@tonconnect/ui-react";
import { TonClient } from "@ton/ton";

async function executeTonDeposit(
  depositAction: any,
  senderAddress: string,
  tonConnectUI: TonConnectUI,
  tonClient: TonClient
) {
  const { token } = depositAction;
  let transaction;

  if (token.contract) {
    transaction = await buildJettonTransaction(
      depositAction,
      senderAddress,
      tonClient
    );
  } else {
    transaction = buildNativeTonTransaction(depositAction);
  }

  const result = await tonConnectUI.sendTransaction(transaction);

  // result.boc contains the sent message BOC
  // You can use it to track the transaction on-chain
  return result.boc;
}
The server-side example above shows a native TON transfer. For Jetton transfers, build the Jetton cell as shown in the Jetton section and target the sender’s Jetton wallet address.

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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.