eth_call

eth_call runs a message call against OP Mainnet's EVM and returns the result without broadcasting a transaction or spending any ETH gas. It executes against the rollup state at a chosen block, so it is the workhorse for reading contracts — token balances, DEX reserves, on-chain view functions — on this OP Stack chain. Point the request at https://optimism.therpc.io/YOUR_API_KEY (chain ID 10, 0xa); the node simulates the call locally and returns the ABI-encoded return data, leaving chain state untouched.

Use cases

• Read ERC-20 balanceOf, decimals, symbol, or totalSupply for tokens deployed on OP Mainnet.
• Query Velodrome pool reserves or spot prices, or any DEX getReserves-style view, to price assets on the Superchain.
• Simulate a transaction outcome against latest state before signing to catch reverts early and save the user a failed L2 fee.
• Apply state overrides (third argument) to model what-if scenarios — a different balance or contract code — without touching OP Mainnet state.

Parameters

Response

Example request

1curl https://optimism.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": "0x0000000000000000000000000000000000000000",
10          "data": "0x"
11        },
12        "latest",
13        {}
14      ],
15    "id": 1
16  }'

Try it live in the Optimism playground.

Errors & troubleshooting

Common pitfalls

• OP Mainnet's latest state advances roughly every 2 seconds, so a result read now can be stale by the time your transaction is sequenced — treat the value as a snapshot, not a guarantee.
• The stateOverrides third argument is not supported by every provider; detect the failure and fall back to a plain call without overrides.
• A reverted call comes back as a JSON-RPC error (code 3 or -32000), not as a special result field — always handle the error path and decode the revert reason from the error data.

Supported networks

• Mainnet — Chain ID: 10
• Sepolia — Chain ID: 11155420

See also

• eth_estimateGas
• eth_sendRawTransaction
• eth_getStorageAt

1curl https://optimism.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H 'Content-Type: application/json' \
4  -d '{"jsonrpc":"2.0","id":1,"method":"eth_call","params":[{"to":"0x0000000000000000000000000000000000000000","data":"0x"},"latest"]}'