debug_traceCall

debug_traceCall executes a call against a chosen OP Mainnet block state and returns a full opcode-level trace — all without broadcasting a transaction or spending any ETH. It is the simulation counterpart to debug_traceTransaction: you describe a call (the same fields as eth_call), pick a block to run it against, and the node traces the result, optionally applying state and block overrides. On OP Mainnet — the OP Stack rollup with ETH gas, chain ID 10 (0xa) — point the request at https://optimism.therpc.io/YOUR_API_KEY to preview exactly how a contract interaction would behave before you commit to it.

Use cases

• Debug an OP Mainnet contract interaction before broadcasting by tracing the exact execution path and any revert reason.
• Simulate how a call would behave at a historical block height (past blocks require an archive node).
• Profile the gas a prospective transaction would consume without spending any ETH.
• Test proposed contract logic against live OP Mainnet state using state overrides, before deploying the change.

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": "debug_traceCall",
7    "params": [
8        {
9          "to": "0x0000000000000000000000000000000000000000",
10          "data": "0x"
11        },
12        "latest",
13        {},
14        {},
15        {}
16      ],
17    "id": 1
18  }'

Try it live in the Optimism playground.

Errors & troubleshooting

Common pitfalls

• The trace runs against the specified block's state, so results can differ from real execution if the call depends on block context such as coinbase, timestamp, or base fee — override these explicitly when it matters.
• Simulating against a historical OP Mainnet block requires an archive node; a pruned node only has recent state.
• Responses can be huge for complex contracts; use a compact tracer like callTracer or disable stack/memory/storage in the options to keep output small.

Supported networks

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

See also

• debug_traceTransaction
• trace_call
• debug_storageRangeAt
• debug_traceBlockByNumber

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":"debug_traceCall","params":[{"to":"0x0000000000000000000000000000000000000000","data":"0x"},"latest",{}]}'