Cross-chain dapp testing is significantly more time-consuming than single-chain dapp testing. Developers would typically deploy smart contracts to supported networks on testnet, submit a cross-chain transaction to the deployed contract, wait for our network to relay the transaction to the destination chain, and then check the result at your destination contract.
The complete process normally takes about 2-3 minutes on the Testnet. It is too slow when the destination chain's smart contract contains unknown problems that needs be debugged by developers. Axelar Sandbox offers simulated settings that minimize block time and automatically relay transactions without the need for validators. As a result, developers may reduce the time it takes from start to finish from 2-3 minutes to 10 seconds.
The sandbox app can be found at https://xchainbox.axelar.dev
To learn more, please continue reading how-to-use doc.