eth_call

eth_call runs a message call through the Ethereum Virtual Machine and hands back the return data, all without broadcasting anything or burning a single wei of ETH. The call executes against state at a block you choose, then the result is discarded — nothing is written, no nonce moves, no gas leaves your account. This is how every dApp reads contract storage on Ethereum mainnet: token balances, pool reserves, allowance checks, view functions of any kind. Send the request to https://ethereum.therpc.io/YOUR_API_KEY (chain ID 1) with ABI-encoded calldata in the data field and decode the hex you get back with the contract's ABI.

Use cases

Read ERC-20 metadata and balances. balanceOf, decimals, symbol, totalSupply — the four calls every wallet makes to render a token row are all eth_call under the hood.
Price discovery. Hit a Uniswap pair's getReserves or a router's getAmountsOut to compute a spot quote without quoting on-chain.
Pre-flight a transaction. Replay the exact calldata you're about to sign against latest state to catch a revert before you pay for it.
What-if simulation. Use the stateOverrides argument to fake a balance, swap in different bytecode, or rewrite a storage slot, then see how the call behaves — all on a throwaway copy of state.

Parameters

#	Name	Type	Required	Description
1	`transaction`	object	Yes	Transaction object. Required fields: `to` (target contract). Optional: `from` (msg.sender), `gas` (hex), `gasPrice` (hex), `value` (hex wei), `data` (ABI-encoded calldata).
2	`blockTag`	string \| object	Yes	Block at which to execute the call. Use hex block number or a named tag.Default: `latest`
3	`stateOverrides`	object	No	Optional map of address → { balance, nonce, code, state, stateDiff } overrides applied only for this call. Not supported by all providers.

Response

Type	Description
string	Hex-encoded return data from the executed function. Decode with the contract ABI. If the call reverts, an error with code -32000 or 3 is returned instead.

Example request

1curl https://ethereum.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H "Content-Type: application/json" \
4  -d '{
5    "jsonrpc": "2.0",
6    "method": "eth_call",
7    "params": [
8        {
9          "to": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
10          "data": "0x"
11        },
12        "latest",
13        {}
14      ],
15    "id": 1
16  }'

Try it live in the Ethereum playground.

Errors & troubleshooting

Code	Message	Cause
`3`	`execution reverted`	The EVM reverted the call. Error data contains the revert reason.
`-32602`	`invalid argument`	Malformed transaction object or missing required `to` field.
`-32000`	`execution reverted`	Node-level revert without revert data (e.g. out-of-gas within the call, or require with no message).

Common pitfalls

A result read at latest is a snapshot. By the time your signed transaction lands a slot or two later, the same call can return something else — never treat an eth_call quote as a settlement guarantee.
The stateOverrides third argument is a node extension, not part of the base JSON-RPC spec. Some backends ignore it or reject it; detect that and degrade to a plain call rather than assuming it took effect.
A revert comes back as a JSON-RPC error (code 3 with revert data, or -32000 when there's no reason string), not as a normal return value. Always wire up the error path, decoding the revert reason where it exists.

Supported networks

Mainnet — Chain ID: 1
Sepolia — Chain ID: 11155111