🛠️ Supersim

Supersim is a lightweight tool to simulate the Superchain locally (with a single L1 and multiple OP-Stack L2s).

✨ Features

• spin up multiple anvil nodes
• predeployed OP Stack contracts and useful mock contracts (ERC20)
• fork multiple remote chains (fork the entire Superchain)
• simulate L1 <> L2 message passing (deposits) and L2 <> L2 message passing (interoperability)

For detailed instructions and usage guides, refer to the 📚 Supersim docs.

🚀 Getting Started

1. Install prerequisites: foundry

supersim requires anvil to be installed.

Follow this guide to install Foundry.

2. Install supersim

Homebrew (OS X, Linux)

brew install ethereum-optimism/tap/supersim

Precompiled Binaries

Download the executable for your platform from the GitHub releases page.

3. Start supersim in vanilla mode

supersim

Vanilla mode will start 3 chains, with the OP Stack contracts already deployed.

Chain Configuration
-----------------------
L1: Name: Local  ChainID: 900  RPC: http://127.0.0.1:8545  LogPath: /var/folders/y6/bkjdghqx1sn_3ypk1n0zy3040000gn/T/anvil-chain-900-3719464405

L2s: Predeploy Contracts Spec ( https://specs.optimism.io/protocol/predeploys.html )

  * Name: OPChainA  ChainID: 901  RPC: http://127.0.0.1:9545  LogPath: /var/folders/y6/bkjdghqx1sn_3ypk1n0zy3040000gn/T/anvil-chain-901-1956365912
    L1 Contracts:
     - OptimismPortal:         0xF5fe61a258CeBb54CCe428F76cdeD04Cbc12F53d
     - L1CrossDomainMessenger: 0xe5bda89cd85cE0DfB80E053281cA070D65B738e6
     - L1StandardBridge:       0xa01ae68902e205B420FD164435F299E07b0C778b

  * Name: OPChainB  ChainID: 902  RPC: http://127.0.0.1:9546  LogPath: /var/folders/y6/bkjdghqx1sn_3ypk1n0zy3040000gn/T/anvil-chain-902-1214175152
    L1 Contracts:
     - OptimismPortal:         0xdfC9DEAbEEbDaa7620C71e2E76AEda32919DE5f2
     - L1CrossDomainMessenger: 0xCB9768921831677Ae15cE4B64A10B94F49cD88E2
     - L1StandardBridge:       0x2D8543c236a4d626f54B51Fa8bc229a257C5143E

4. Start testing multichain features 🚀

Some examples below!

🔀 First steps

Example A: (L1 to L2) Deposit ETH from the L1 into the L2

1. Check initial balance on the L2 (chain 901)

Grab the balance of the sender account on L2:

cast balance 0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266 --rpc-url http://127.0.0.1:9545

2. Call bridgeETH function on the L1StandardBridgeProxy contract on the L1 (chain 900)

Initiate a bridge transaction on the L1:

cast send 0xa01ae68902e205B420FD164435F299E07b0C778b "bridgeETH(uint32 _minGasLimit, bytes calldata _extraData)" 50000 0x --value 0.1ether --rpc-url http://127.0.0.1:8545 --private-key 0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80

3. Check the balance on the L2 (chain 901)

Verify that the ETH balance of the sender has increased on the L2:

cast balance 0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266 --rpc-url http://127.0.0.1:9545

Example B: (L2 to L2) Send an interoperable SuperchainERC20 token from chain 901 to 902

In a typical L2 to L2 cross-chain transfer, two transactions are required:

1. Send transaction on the source chain – This initiates the token transfer on Chain 901.
2. Relay message transaction on the destination chain – This relays the transfer details to Chain 902.

To simplify this process, you can use the --interop.autorelay flag. This flag automatically triggers the relay message transaction once the initial send transaction is completed on the source chain, improving the developer experience by removing the need to manually send the relay message.

1. Start supersim with the autorelayer enabled.

supersim --interop.autorelay 

2. Mint tokens to transfer on chain 901 Run the following command to mint 1000 L2NativeSuperchainERC20 tokens to the recipient address:

cast send 0x420beeF000000000000000000000000000000001 "mint(address _to, uint256 _amount)"  0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266 1000  --rpc-url http://127.0.0.1:9545 --private-key 0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80

3. Initiate the send transaction on chain 901

Send the tokens from Chain 901 to Chain 902 using the following command:

cast send 0x420beeF000000000000000000000000000000001 "sendERC20(address _to, uint256 _amount, uint256 _chainId)" 0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266 1000 902 --rpc-url http://127.0.0.1:9545 --private-key 0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80

4. Wait for the relayed message to appear on chain 902

In a few seconds, you should see the RelayedMessage on chain 902:

# example
INFO [08-30|14:30:14.698] L2ToL2CrossChainMessenger#RelayedMessage sourceChainID=901 destinationChainID=902 nonce=0 sender=0x420beeF000000000000000000000000000000001 target=0x420beeF000000000000000000000000000000001

5. Check the balance on chain 902

Verify that the balance of the L2NativeSuperchainERC20 on chain 902 has increased:

cast balance --erc20 0x420beeF000000000000000000000000000000001 0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266 --rpc-url http://127.0.0.1:9546

For more detailed instructions and usage guides, refer to the 📚 Supersim docs.

🌐 Fork mode

If you're relying on contracts already deployed on testnet / mainnet chains, use fork mode to simulate and interact with the state of the chain without needing to re-deploy or modify the contracts.

Locally fork any of the available chains in a superchain network of the superchain registry, default mainnet versions.

supersim fork --chains=op,base,zora

The fork height is determined by L1 block height (default latest), which determines the maximum timestamp for the forked L2 state of each chain.

Chain Configuration
-----------------------
L1: Name: mainnet  ChainID: 1  RPC: http://127.0.0.1:8545  LogPath: /var/folders/y6/bkjdghqx1sn_3ypk1n0zy3040000gn/T/anvil-chain-1-832151416

L2s: Predeploy Contracts Spec ( https://specs.optimism.io/protocol/predeploys.html )

  * Name: op  ChainID: 10  RPC: http://127.0.0.1:9545  LogPath: /var/folders/y6/bkjdghqx1sn_3ypk1n0zy3040000gn/T/anvil-chain-10-2710239022
    L1 Contracts:
     - OptimismPortal:         0xbEb5Fc579115071764c7423A4f12eDde41f106Ed
     - L1CrossDomainMessenger: 0x25ace71c97B33Cc4729CF772ae268934F7ab5fA1
     - L1StandardBridge:       0x99C9fc46f92E8a1c0deC1b1747d010903E884bE1

  * Name: base  ChainID: 8453  RPC: http://127.0.0.1:9546  LogPath: /var/folders/y6/bkjdghqx1sn_3ypk1n0zy3040000gn/T/anvil-chain-8453-1054019892
    L1 Contracts:
     - OptimismPortal:         0x49048044D57e1C92A77f79988d21Fa8fAF74E97e
     - L1CrossDomainMessenger: 0x866E82a600A1414e583f7F13623F1aC5d58b0Afa
     - L1StandardBridge:       0x3154Cf16ccdb4C6d922629664174b904d80F2C35

  * Name: zora  ChainID: 7777777  RPC: http://127.0.0.1:9547  LogPath: /var/folders/y6/bkjdghqx1sn_3ypk1n0zy3040000gn/T/anvil-chain-7777777-1949580962
    L1 Contracts:
     - OptimismPortal:         0x1a0ad011913A150f69f6A19DF447A0CfD9551054
     - L1CrossDomainMessenger: 0xdC40a14d9abd6F410226f1E6de71aE03441ca506
     - L1StandardBridge:       0x3e2Ea9B92B7E48A52296fD261dc26fd995284631

Development

Running locally

go run cmd/main.go

Building locally

1. build the binary by running:

go build cmd/main.go

2. start supersim in vanilla mode by running:

./main

Note

By default, interop contracts are not deployed on forked networks. To include them, run supersim with the --interop.enabled flag

supersim fork --chains=op,base,zora --interop.enabled

❓ Why Supersim?

While existing tools focus on isolated smart contract testing, Supersim provides a local development environment that mirrors the complex interactions of the Superchain ecosystem. Simulate entire cross-chain application flows, complete with deployed contracts, intricate message passing infrastructure, and OP-Stack specific logic with one command.

Multichain development offers unique challenges:

• Coordinating startup and running multiple local chains
• Deploying system contracts to mimic desired functionality
• Running local offchain services like message relayers

Supersim enables fast, local iteration on cross-chain features, with a simple developer interface.

🤝 Contributing

Contributions are encouraged, but please open an issue before making any major changes to ensure your changes will be accepted.

See CONTRIBUTING.md for contributing information.

📜 License

Files are licensed under the MIT license.