Multi-Block Simulation Runner

WHAT IT DOES

The Multi-Block Simulation Runner is a developer tool that simulates multiple transactions across a sequence of blocks on a forked blockchain state. It creates a forked state from an RPC provider at a specified start block, then runs a user-defined sequence of transactions across multiple blocks, tracking gas estimates and transaction results for each step. This helps developers test complex multi-step interactions, contract upgrade sequences, and time-dependent logic that spans multiple blocks.

HOW TO USE

Enter an RPC URL and start block number for the fork. Set the number of blocks to simulate. Click "create fork" to establish the forked state. Enter your transaction sequence with each transaction on a new line in the format: from,to,data,value (value is optional, default 0). Click "run simulation" to execute the transactions across the simulated block sequence. The tool displays results per block, showing each transaction's success status, gas estimate, and any errors encountered.

TECHNICAL MECHANISM

The tool creates a JsonRpcProvider connected to the provided RPC URL and verifies the start block exists. It parses the transaction sequence from user input, extracting from address, to address, call data, and value for each transaction. The simulation iterates through each block in the sequence: for each block, it processes all transactions in the sequence in order. For each transaction, the tool uses the provider's estimateGas() method to estimate gas consumption and call() to simulate execution. The simulation preserves the forked state across blocks, allowing state changes from earlier transactions to affect later ones. The tool tracks which transactions succeed or fail, captures gas estimates, and reports errors. Results are presented per block with transaction-level details and overall summary statistics.

WHAT IT CANNOT SEE

The tool cannot execute transactions on the live network. It cannot guarantee that simulation results will match live execution due to forking differences. The tool cannot account for real-time state changes during simulation. It cannot predict gas costs accurately without actual execution. The tool cannot detect issues that depend on real-time network conditions. It cannot validate that the forked state is an exact replica of the historical block. The tool cannot handle state changes that depend on block timestamps or difficulty without manual override. It cannot simulate more blocks than the provider supports in a single fork.

PLEASE NOTE

This tool is designed for Ethereum Virtual Machine (EVM) compatible chains. The forked state is created by querying the RPC provider—the provider must support archival data access for historical blocks. The tool simulates the provided transaction sequence for each block, repeating the same sequence across all blocks. For more complex sequences where different transactions should occur in different blocks, users should run separate simulations. The tool provides estimates only and should be used for debugging and testing purposes. Always verify simulation results against live execution on testnet.