> ## Documentation Index > Fetch the complete documentation index at: https://docs.tenderly.co/llms.txt > Use this file to discover all available pages before exploring further. # Simulate Blocks with eth_simulateV1 > Simulate a sequence of blocks with batched calls, state overrides, and block overrides using the standard eth_simulateV1 JSON-RPC method. `eth_simulateV1` is the standard multi-block simulation method from the [Ethereum execution APIs](https://github.com/ethereum/execution-apis) specification. It simulates a sequence of blocks, each containing a batch of calls, on top of a base block, without sending anything on chain. Calls within a block execute sequentially and share state, and each simulated block builds on the previous one. The method runs on [Node RPC](/node-rpc/overview) and [Virtual Environments](/virtual-environments/overview); see the full [JSON-RPC reference](/node-rpc/rpc-reference) for every method and network. A small set of networks does not support it; see [Network availability](#network-availability). Use `eth_simulateV1` when you need a portable, spec-standard simulation that returns block-shaped results. For decoded logs, call traces, and asset and balance changes, use [`tenderly_simulateTransaction`](/node-rpc/guides/simulate-json-rpc) for a single transaction or [`tenderly_simulateBundle`](/node-rpc/guides/simulate-bundle-json-rpc) for a sequence of transactions. ### `eth_simulateV1` Simulates a sequence of blocks on top of the given base block. Each block contains a batch of calls: call N sees the state changes of call N-1, and every block after the first builds on the block before it. **Params** 1. **Simulation payload** `OBJECT` * **blockStateCalls** `ARRAY` of Block state call `OBJECT`: the sequence of blocks to simulate, in order * **blockOverrides** (*optional*) `OBJECT`: the set of header fields to override in this block * **number** (*optional*) `STRING`: hex, overrides the block number * **difficulty** (*optional*) `STRING`: hex, overrides the block difficulty * **time** (*optional*) `STRING`: hex, overrides the block timestamp * **gasLimit** (*optional*) `STRING`: hex, overrides the gas limit * **coinbase** (*optional*) `STRING`: hex, overrides the block miner * **random** (*optional*) `STRING`: hex, overrides the value that feeds into the PREVRANDAO opcode * **baseFee** (*optional*) `STRING`: hex, overrides the block base fee * **excessBlobGas** (*optional*) `STRING`: hex, overrides the excess blob gas * **blobGasUsed** (*optional*) `STRING`: hex, overrides the blob gas used * **stateOverrides** (*optional*) `MAP`: mapping from an account (address) to override specification. Set state overrides on the **first** block entry; see [Tenderly-specific behavior](#tenderly-specific-behavior) * **key** `STRING`: the account this override applies to * **value** `OBJECT`: the override specification * **balance** (*optional*) `STRING`: hex encoded balance override for the account in wei * **nonce** (*optional*) `STRING`: hex encoded nonce override for the account * **code** (*optional*) `STRING`: data of the code override for the account * **stateDiff** (*optional*) `MAP`: mapping of storage key to storage value override * **key** `STRING`: the storage key * **value** `STRING`: the value override for the given storage key * **calls** `ARRAY` of Transaction call `OBJECT`: executed in order; each call observes the state changes of the calls before it * **from** (*optional*) `STRING`: hex encoded address; defaults to the zero address * **to** (*optional*) `STRING`: hex encoded address * **gas** (*optional*) `STRING`: hex encoded gas limit for the call * **gasPrice** (*optional*) `STRING`: hex, the gas price willing to be paid by the sender in wei * **maxFeePerGas** (*optional*) `STRING`: hex, the maximum total fee per gas the sender is willing to pay (includes the network / base fee and miner / priority fee) in wei * **maxPriorityFeePerGas** (*optional*) `STRING`: hex, the maximum fee per gas the sender is willing to pay to miners in wei * **value** (*optional*) `STRING`: hex encoded value in wei; defaults to `0x0` * **input** (*optional*) `STRING`: hex encoded call data; `data` is accepted as a deprecated alias, and `input` takes precedence when both are set * **nonce** (*optional*) `STRING`: hex encoded nonce * **type** (*optional*) `STRING`: hex encoded transaction type * **accessList** (*optional*) `ARRAY` of Access list entry `OBJECT` * **address** `STRING`: hex encoded address * **storageKeys** `ARRAY` of `STRING`: representation of 32 byte hex encoded storage keys * **maxFeePerBlobGas** (*optional*) `STRING`: hex, the maximum fee per blob gas in wei * **blobVersionedHashes** (*optional*) `ARRAY` of `STRING`: 32 byte hex encoded blob versioned hashes * **authorizationList** (*optional*) `ARRAY`: EIP-7702 authorization tuples * **returnFullTransactions** (*optional*) `BOOLEAN`: when `true`, result blocks contain full transaction objects instead of transaction hashes 2. **Base block number** (*optional*) The block on top of which the simulation runs. Defaults to `latest`. Either: * `STRING` Block number * `ENUM` of Block tag `earliest|finalized|safe|latest|pending` **Example** The request simulates two blocks. The first block funds a sender with a state override, then sends ETH and wraps 1 ETH into WETH; the second block sets a custom timestamp and transfers the WETH minted in the first block. ```json title="example.json" showLineNumbers theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} { "id": 0, "jsonrpc": "2.0", "method": "eth_simulateV1", "params": [ { "blockStateCalls": [ { "stateOverrides": { "0xe2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2": { "balance": "0x3635c9adc5dea00000" } }, "calls": [ { "from": "0xe2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2", "to": "0x1111111111111111111111111111111111111111", "value": "0x1bc16d674ec80000" }, { "from": "0xe2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2", "to": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2", "value": "0xde0b6b3a7640000", "input": "0xd0e30db0" } ] }, { "blockOverrides": { "time": "0x6ae00000" }, "calls": [ { "from": "0xe2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2", "to": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2", "input": "0xa9059cbb00000000000000000000000011111111111111111111111111111111111111110000000000000000000000000000000000000000000000000de0b6b3a7640000" } ] } ] }, "latest" ] } ``` ```bash title="example" showLineNumbers theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} curl https://mainnet.gateway.tenderly.co/$TENDERLY_NODE_ACCESS_KEY \ -X POST \ -H "Content-Type: application/json" \ -d \ '{ "id": 0, "jsonrpc": "2.0", "method": "eth_simulateV1", "params": [ { "blockStateCalls": [ { "stateOverrides": { "0xe2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2": { "balance": "0x3635c9adc5dea00000" } }, "calls": [ { "from": "0xe2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2", "to": "0x1111111111111111111111111111111111111111", "value": "0x1bc16d674ec80000" }, { "from": "0xe2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2", "to": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2", "value": "0xde0b6b3a7640000", "input": "0xd0e30db0" } ] }, { "blockOverrides": { "time": "0x6ae00000" }, "calls": [ { "from": "0xe2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2", "to": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2", "input": "0xa9059cbb00000000000000000000000011111111111111111111111111111111111111110000000000000000000000000000000000000000000000000de0b6b3a7640000" } ] } ] }, "latest" ] }' ``` ```javascript title="example.js" showLineNumbers theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} // Installation Instructions: https://docs.ethers.io/v5/getting-started/#installing const { ethers } = require('ethers'); async function runSimulateV1() { // Initialize an ethers instance const provider = new ethers.providers.JsonRpcProvider( 'https://mainnet.gateway.tenderly.co/$TENDERLY_NODE_ACCESS_KEY', ); // Execute method const result = await provider.send('eth_simulateV1', [ { blockStateCalls: [ { stateOverrides: { '0xe2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2': { balance: '0x3635c9adc5dea00000', }, }, calls: [ { from: '0xe2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2', to: '0x1111111111111111111111111111111111111111', value: '0x1bc16d674ec80000', }, { from: '0xe2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2', to: '0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2', value: '0xde0b6b3a7640000', input: '0xd0e30db0', }, ], }, { blockOverrides: { time: '0x6ae00000' }, calls: [ { from: '0xe2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2', to: '0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2', input: '0xa9059cbb00000000000000000000000011111111111111111111111111111111111111110000000000000000000000000000000000000000000000000de0b6b3a7640000', }, ], }, ], }, 'latest', ]); // Print the output to console console.log(result); } (async () => { runSimulateV1(); })(); ``` ```json title="response.json" showLineNumbers theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} { "id": 0, "jsonrpc": "2.0", "result": [ { "number": "0x184b35b", "hash": "0x2b33857d4b0380d7b92a258c77d9357c9515701f914684789e959ae84d73347a", "parentHash": "0x1fe7faf7d5b3a57fe52192bcf634b62bda8cfd39a5509d5541a2fb30d5438463", "nonce": "0x88425305eb52b6f7", "mixHash": "0x5bf018c82ca9e0e3805b00475afe61be2b1077eff79abb6cb4617af8548aa514", "sha3Uncles": "0x0000000000000000000000000000000000000000000000000000000000000000", "logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000", "stateRoot": "0x0000000000000000000000000000000000000000000000000000000000000000", "miner": "0x4838b106fce9647bdf1e7877bf73ce8b0bad5f97", "difficulty": "0x0", "extraData": "0x546974616e2028746974616e6275696c6465722e78797a29", "size": "0x0", "gasLimit": "0x3938700", "gasUsed": "0x3938700", "timestamp": "0x6a4bb197", "transactionsRoot": "0x0000000000000000000000000000000000000000000000000000000000000000", "receiptsRoot": "0x0000000000000000000000000000000000000000000000000000000000000000", "baseFeePerGas": "0x18d7ee41", "blobGasUsed": "0x60000", "excessBlobGas": "0xba42085", "uncles": [], "transactions": [ "0xbb42f5dcbfa507c52b64642c9b9e2a95fc4e2542cbd06b180239367d45f35e30", "0xcb06f645c2962f5dfff047efb2a000d05d0a58a619c63c97ec3e12cf48d02033" ], "calls": [ { "returnData": "0x", "logs": [], "gasUsed": "0x5208", "status": "0x1" }, { "returnData": "0x", "logs": [ { "address": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2", "topics": [ "0xe1fffcc4923d04b559f4d29a8bfc6cda04eb5b0d3c460751c2402c5c5cc9109c", "0x000000000000000000000000e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2" ], "data": "0x0000000000000000000000000000000000000000000000000de0b6b3a7640000", "blockNumber": "0x184b35b", "transactionHash": "0xcb06f645c2962f5dfff047efb2a000d05d0a58a619c63c97ec3e12cf48d02033", "transactionIndex": "0x1", "blockHash": "0x2b33857d4b0380d7b92a258c77d9357c9515701f914684789e959ae84d73347a", "logIndex": "0x0", "removed": false } ], "gasUsed": "0xafee", "status": "0x1" } ] }, { "number": "0x184b35c", "hash": "0xddb8a8a01c753b30acea4c8a12e36f3157dfa854ad0134b1dbb1e6227a9838cd", "parentHash": "0x2b33857d4b0380d7b92a258c77d9357c9515701f914684789e959ae84d73347a", "nonce": "0x0000000000000000", "mixHash": "0x5bf018c82ca9e0e3805b00475afe61be2b1077eff79abb6cb4617af8548aa514", "sha3Uncles": "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347", "logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000", "stateRoot": "0x0000000000000000000000000000000000000000000000000000000000000000", "miner": "0x0000000000000000000000000000000000000000", "difficulty": "0x0", "extraData": "0x546974616e2028746974616e6275696c6465722e78797a29", "size": "0x18e", "gasLimit": "0x3938700", "gasUsed": "0x0", "timestamp": "0x6ae00000", "transactionsRoot": "0x0000000000000000000000000000000000000000000000000000000000000000", "receiptsRoot": "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421", "baseFeePerGas": "0x1bf2ec09", "excessBlobGas": "0xba62085", "uncles": [], "transactions": [ "0x21ac69b18844a9f1345c2b29292852477672178b0d338092f20dcb850d261604" ], "calls": [ { "returnData": "0x0000000000000000000000000000000000000000000000000000000000000001", "logs": [ { "address": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2", "topics": [ "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef", "0x000000000000000000000000e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2e2", "0x0000000000000000000000001111111111111111111111111111111111111111" ], "data": "0x0000000000000000000000000000000000000000000000000de0b6b3a7640000", "blockNumber": "0x184b35b", "transactionHash": "0x21ac69b18844a9f1345c2b29292852477672178b0d338092f20dcb850d261604", "transactionIndex": "0x0", "blockHash": "0x2b33857d4b0380d7b92a258c77d9357c9515701f914684789e959ae84d73347a", "logIndex": "0x1", "removed": false } ], "gasUsed": "0x73fe", "status": "0x1" } ] } ] } ``` **Result** `ARRAY` of Block result `OBJECT`, one per `blockStateCalls` entry, in order. Each block result carries the standard block header fields returned by `eth_getBlockByNumber` (`number`, `hash`, `parentHash`, `timestamp`, `gasLimit`, `gasUsed`, `baseFeePerGas`, `logsBloom`, `miner`, and so on) plus: * **transactions** `ARRAY`: transaction hashes of the simulated calls, or full transaction objects when `returnFullTransactions` is `true` * **calls** `ARRAY` of Call result `OBJECT`, one per call, in order: * **returnData** `STRING`: hex encoded return data of the call * **logs** `ARRAY` of Log `OBJECT`: events emitted by the call (`address`, `topics`, `data`, `blockNumber`, `transactionHash`, `transactionIndex`, `blockHash`, `logIndex`, `removed`); empty for reverted calls * **gasUsed** `STRING`: hex encoded amount of gas consumed by the call * **status** `STRING`: `0x1` for success, `0x0` for failure * **error** `OBJECT`: present only when the call fails * **code** `NUMBER`: error code * **message** `STRING`: error message, including the revert reason when available ### Tenderly-specific behavior The Tenderly implementation deviates from the reference [execution-apis](https://github.com/ethereum/execution-apis) specification in the following ways: * **`validation` is not supported.** Setting `validation: true` returns the error `validation flag is not supported`. Simulation always runs in non-validating mode: nonce, balance, and fee requirements are not enforced on the calls. * **`traceTransfers` is not supported.** Setting `traceTransfers: true` returns the error `traceTransfers flag is not supported`. No synthetic ETH transfer logs are produced. * **`state` overrides are not supported.** The `state` field (full storage replacement) in a state override returns a `not supported` error. Use `stateDiff` to override individual storage slots. * **State overrides apply from the first block.** Set `stateOverrides` on the first `blockStateCalls` entry; `stateOverrides` on subsequent entries are not applied. * **Per-call `gas` is clamped.** A `gas` value above the block gas limit plus 600,000,000 is clamped to that ceiling instead of being rejected. * **No block or call count limits.** There is no enforced maximum on the number of `blockStateCalls` entries or on the number of calls per block. * **Transaction hashes are synthetic.** The hashes in result blocks identify the simulated calls but are not hashes of signed transactions. * **Block progression.** Each simulated block after the first gets `number = previous + 1` and a `parentHash` chained to the previous result, with the base fee and gas limit recomputed. The auto-generated timestamp is the node's wall-clock time, so set `blockOverrides.time` explicitly when timestamps matter. Overridden block numbers and timestamps are applied verbatim; monotonicity is not validated. When the first block entry supplies `blockOverrides` without `number`, the block number defaults to the base block plus 1. ### Network availability `eth_simulateV1` is available on Node RPC networks and Virtual Environments, except on the following networks, where the underlying network nodes do not support the method: * ApeChain * Avalanche C-Chain * Avalanche C-Chain Fuji * Blast * Curtis * Flare * Immutable * Immutable Testnet * Lens * Lens Testnet * Metis Andromeda * Metis Sepolia * Monad * Monad Testnet * Moonbase Alpha * Moonbeam * Moonriver * Scroll Mainnet * Scroll Sepolia * Sonic * Sonic Testnet * Stable * Stable Testnet * ZKsync * ZKsync Sepolia