Getting Familiar with Sandbox UI (Alpha version)

The Axelar Sandbox UI is divided into four panels.

Solidity editor (top left) — Write your Solidity smart contract code here. Currently, only two smart contracts can be compiled. We’ll allow developer to add more smart contracts soon.

JavaScript editor (top right) — Write the JavaScript code that deploys and interacts with the smart contracts.

JavaScript console output (bottom right) — This is where you’ll see the output of the JavaScript execution as well as any errors that occurred.

Transactions overview (bottom left) — a list of transactions that occurred as a result of your Solidity and JavaScript code, including with transaction data such as event logs, function calls, and function arguments

How to use it?

Let’s begin by executing our examples. So, here’s how the website looks like:


  1. We have some built-in examples at the bottom left that the developer can play with without modifying anything.


  1. hello-world is the default example. It shows how to update destination contract states from the source chain contract. The example can be run against testnet or simulated environment.


  1. Clicks at the Execute button in the upper right corner to run an example.


  1. Next, the solidity contracts will be compiled; if successful, the javascript file will be executed; otherwise, the error message will be displayed. The “Output” panel displays all Javascript log messages that have already been executed.


  1. The ”Transactions” panel displays all transaction info sent from the ”sender” and the ”relayer” wallet. The relayer wallet is the wallet that interacts with your destination contract while the sender does that with the source contract. The transaction information includes:
  • Transaction hash
  • Transaction status
  • Source address
  • Destination address
  • Function name
  • Function arguments
  • Emitted event data

The image below shows how it looks like.


Using Javascript to interact with smart contracts

You can use ethers.js to deploy and interact with your smart contracts using Javascript. ethers variable is automatically injected into the js code editor.

Available JavaScript global variables

You can use the global variables listed below anywhere in your JavaScript code.


An enum representation of string value of chain name. The snippet below expands all available chains.

Chain.ETHEREUM; // ethereum
Chain.AVALANCHE; // avalanche
Chain.FANTOM; // fantom
Chain.MOONBEAM; // moonbeam
Chain.POLYGON; // polygon


A map of contracts representing compiled contracts including abi and bytecode. The map is indexed by the smart contract name defined in the Solidity file.

// access to MessageSender contract's abi
// access to MessageReceiver contract's bytecode


A map of abis for commonly used contracts.

const { erc20, gateway, gasReceiver } = $abis;


A signer account for given chain.

const ethereumSigner = await $getSigner(Chain.ETHEREUM);
const avalancheSigner = await $getSigner(Chain.AVALANCHE);


A map of chains info which uses Chain as a key. The snippet below expands all available chain values.

const { rpcUrl, gateway, gasReceiver, tokens } = $chains[Chain.ETHEREUM];
const { aUSDC } = tokens;

// instantiate a provider
const provider = new ethers.providers.JsonRpcProvider(rpcUrl);

// instantiate a gateway contract
const gatewayContract = new ethers.Contract(gateway, $abis.gateway, provider);

// instantiate a gas receiver contract
const gasReceiverContract = new ethers.Contract(

// instantiate a wrapped usdc contract.
const aUsdcContract = new ethers.Contract(aUSDC, $abis.erc20, provider);

Deploy a Contract

The following code is the example of how to deploy a smart contract that we wrote in “MessageSender.sol” file.

const signer = await $getSigner(Chain.MOONBEAM);
const contractFactory = new ethers.ContractFactory(
const contract = await srcContractFactory.deploy(

That’s all we have for now. The Axelar Sandbox is still in its early stages of development. We intend to improve it further in the future. Keep an eye out. 👀

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