Simulates user operations and returns a list of asset changes.
Network Support
| Chain | Mainnet | Testnet |
|---|---|---|
| Ethereum | ✅ 1 (eth-mainnet) | ✅ 11155111 (eth-sepolia) |
| Polygon | ✅ 137 (polygon-mainnet) | ✅ 80002 (polygon-amoy) |
| Arbitrum | ✅ 42161 (arb-mainnet) | ✅ 421614 (arb-sepolia) |
| Optimism | ✅ 10 (opt-mainnet) | ✅ 11155420 (opt-sepolia) |
| Base | ✅ 8453 (base-mainnet) | ✅ 84532 (base-sepolia) |
Changes in blockchain's state could lead to different outcomes
The results provided by
alchemy_simulateUserOperationAssetChangesare based on the blockchain's state at the moment of simulation. Changes in the blockchain state, such as updates to contract variables or balances, can occur between the time of simulation and when you actually execute yourUserOp.This could lead to different outcomes than predicted. For instance, if a userOp's effect is conditional on the current state of a contract, and this state is altered before the transaction is executed, the final result may not match the simulation.
Please be aware of this potential variance and consider it while using the API.
Dummy Signature
This endpoint requires a dummy signature in the
userOp. Check our FAQs to learn what a dummy signature is and which dummy signature you should use.
This method accepts an array containing a UserOperation Object, an Entrypoint address, and a block override as parameters. However, these 3 items appear three times in the param array below. This has to do with Readme (our docs platform) not supporting multi-type arrays. To workaround, please fill in the userOperation object in the first box, the EntryPoint address in the second box and the Block Override in the third one.