Configuring chains

You can define named chains to use with ZKsync CLI to interact with when running commands.

Every ZKsync CLI command requires a chain to execute transactions on, and by default, the ZKsync Mainnet, ZKsync Sepolia Testnet, in-memory local node, and Dockerized local node are provided. You can add and edit additional chains using the zksync-cli config chains sub-command.

Using a custom chain

The ZKsync CLI prompts with a list of default chains as well as your custom chains whenever you run a command without the --chain option. To pass in a chain to a ZKsync CLI command with the --chain option, use the chain key to refer to the chain of choice.

zksync-cli wallet balance --chain example-chain

Creating a new chain

The CLI prompts you to select an existing chain to edit or the option to add a new chain. Use the arrow keys to navigate to "+ Add new chain" and press Enter to select.

? Select a chain (Use arrow keys)
❯ My ZKchain - my-zkchain
  Custom Chain - custom-chain
  ──────────────
  + Add new chain

The CLI then prompts you with several questions for the new chain. The Chain name is a visual label to identify the chain you are adding, and the Chain key is the id to use for referencing the chain when using the --chain option.

If the chain connects to L1, the CLI will also require the L1 details to setup your new chain configuration.

? Select a chain Add new chain
? Chain id 300
? Chain name Example Chain
? Chain key example-chain
? Chain RPC URL https://sepolia.era.zksync.dev
? Chain explorer URL (optional) https://sepolia.explorer.zksync.io/
? Is this chain connected to L1
  No - skip adding L1 chain info
❯ Yes - add L1 chain info
? Is this chain connected to L1 Yes
? L1 Chain id 11155111
? L1 Chain name Sepolia
? L1 Chain key sepolia
? L1 Chain RPC URL https://rpc.ankr.com/eth_sepolia
? L1 Chain explorer URL (optional) https://sepolia.etherscan.io/
✔ Chain "Example Chain" saved

Edit an existing chain

You can edit an existing custom chain by selecting an existing chain from the prompt after running zksync-cli config chains. Select a chain and the CLI will prompt if you want to Edit or Delete the chain. Press Enter to select the Edit option.

? Select a chain example-chain
? What do you want to do? (Use arrow keys)
❯ Edit
  Delete

The CLI then goes through the prompt similar to creating a new chain, however the initial value will be displayed in parentheses.

? Chain id (300)

To change the initial value, enter a new value and press Enter to move to the next question. To leave the initial value unchanged, press Enter with an empty value.