Send tokens cross-chain

There are three ways to transfer tokens cross-chain with Axelar:

1. Call sendToken from any source chain.
2. Get a deposit address using the AxelarJS SDK.
3. For tokens not natively supported, build your own Interchain Token.

Call sendToken

sendToken is an API method that allows you to send any token supported directly on the Axelar network to any recipient on a destination chain.

The underlying mechanics work slightly differently, depending on whether the origin chain is an EVM chain or a Cosmos-based chain:

sendToken from an EVM Source Chain

1. Locate the Axelar Gateway contract on the source chain.
2. Execute approve on the source chain (ERC-20).
3. Execute sendToken on the Gateway.

1. Locate the Axelar Gateway contract on the source chain

Axelar Gateways are application-layer smart contracts established on source and destination chains. They send and receive payloads, and monitor state. Find a list of Gateway addresses for the chains we support: Mainnet | Testnet.

An Axelar Gateway implements the IAxelarGateway interface, which has a public method called sendToken:

function sendToken(
    string memory destinationChain,
    string memory destinationAddress,
    string memory symbol,
    uint256 amount
) external;

2. Execute approve on the source chain (ERC-20)

Transferring tokens through a Gateway is similar to an ERC-20 token transfer. You first need to approve the Gateway to transfer a specific token in a specific amount. This approval is done via the approve method of the ERC-20 interface:

function approve(address spender, uint256 amount) external returns (bool);

Here, spender is the Gateway address on the source chain.

Find a list of assets, their names and their addresses: Mainnet | Testnet. Note that for the same asset denom, the ERC20 symbol could be different on different chains (e.g. USDC on Ethereum is linked to axlUSDC on Avalanche).

3. Execute sendToken on the Gateway

Call sendToken on the Gateway contract of the source chain. Example:

sendToken(
    "avalanche", // destination chain name
    "0xF16DfB26e1FEc993E085092563ECFAEaDa7eD7fD", // some destination wallet address (should be your own)
    "axlUSDC", // asset symbol, can be differ by chain, see above
    100000000 // amount (in atomic units)
)

Watch for the tokens to appear at the destination address on the destination chain.

sendToken from a Cosmos-based Source Chain

From any Cosmos-based source chain, sendToken is a simple IBC transfer of any asset supported on the Axelar network where the message:

• is sent to the designated admin address on Axelar for receiving GMP (General-Message-Passing) messages - axelar1dv4u5k73pzqrxlzujxg3qp8kvc3pje7jtdvu72npnt5zhq05ejcsn5qme5
• includes a memo field with the following payload:

    {
      destination_chain,
      destination_address,
      payload: null,
      type: 3, // corresponds to the `sendToken` command on Axelar
    }

Using AxelarJS SDK for sendToken

In v0.13.0+ Axelar’s JS SDK abstracts the invocations above in a one-line JS code that can be called directly from any frontend dApp. Example implementations below:

Example: Invoking sendToken using the JS SDK from an EVM chain

import { AxelarAssetTransfer, CHAINS, Environment, SendTokenParams } from "@axelar-network/axelarjs-sdk";
import { ethers, Wallet } from "ethers";

const api = new AxelarAssetTransfer({ environment: Environment.TESTNET });

const getSigner = () => {
  const privateKey = PRIVATE_KEY;
  return new Wallet(privateKey);
};

async function test() {
  const provider = new ethers.providers.JsonRpcProvider(
    "https://api.avax-test.network/ext/bc/C/rpc"
  );
  const signer = getSigner().connect(provider);
  const requestOptions: SendTokenParams = {
    fromChain: CHAINS.TESTNET.AVALANCHE,
    toChain: CHAINS.TESTNET.OSMOSIS,
    destinationAddress: "osmo1x3z2vepjd7fhe30epncxjrk0lehq7xdqe8ltsn",
    asset: { symbol: "aUSDC" },
    amountInAtomicUnits: "5000000",
    options: {
      evmOptions: {
        signer,
        provider,
        txOptions: null as any,
        approveSendForMe: true,
      },
    },
  };
  return api.sendToken(requestOptions);
}

Example: Invoking sendToken using the JS SDK from a Cosmos-based chain

import { AxelarAssetTransfer, CHAINS, Environment, SendTokenParams } from "@axelar-network/axelarjs-sdk";
import { DirectSecp256k1HdWallet } from "@cosmjs/proto-signing";

const api = new AxelarAssetTransfer({ environment: Environment.TESTNET });

const getSigner = async () => {
  const mnemonic = MNEMONIC;
  return DirectSecp256k1HdWallet.fromMnemonic(mnemonic, { prefix: "osmo" });
};

async function test() {
  const offlineSigner = await getSigner();
  const requestOptions: SendTokenParams = {
    fromChain: CHAINS.TESTNET.OSMOSIS,
    toChain: CHAINS.TESTNET.AVALANCHE,
    destinationAddress: "0xB8Cd93C83A974649D76B1c19f311f639e62272BC",
    asset: { denom: "ibc/6F34E1BD664C36CE49ACC28E60D62559A5F96C4F9A6CCE4FC5A67B2852E24CFE" }, //aUSDC
    amountInAtomicUnits: "1000000",
    options: {
      cosmosOptions: {
        cosmosDirectSigner: offlineSigner,
        rpcUrl: "https://rpc.osmotest5.osmosis.zone",
        fee: {
            gas: "250000",
            amount: [{ denom: "uosmo", amount: "30000" }],
        },
      },
    },
  };
  return api.sendToken(requestOptions);
}

Get a deposit address

Use a deposit address if:

• You need functionality not offered by sendToken. Example: Cosmos-to-X.
• You want to allow token transfers from wallets that don’t know anything about Axelar. Example: Withdrawal from a centralized exchange.

You’ll find the SDK method to getDepositAddress as a part of the AxelarJS SDK.