debug_traceCall

debug_traceCall runs a call against a chosen Arbitrum One block state and returns a full opcode-level trace — without ever broadcasting a transaction or spending ETH. You pass an eth_call-style object, pick the block to simulate against, and optionally supply state and block overrides; the node executes it through ArbOS and hands back the trace your tracer config requests. On Arbitrum One (chain ID 42161, an Optimistic Rollup settling to Ethereum L1) this is the fastest way to see exactly why a call would revert or how much gas it would burn before committing. Send requests to https://arbitrum.therpc.io/YOUR_API_KEY.

Use cases

• Debug an Arbitrum One contract interaction before broadcasting by tracing the exact execution path and pinpointing the revert reason.
• Simulate how a call would have behaved at a historical Arbitrum One block height (past blocks require an archive node with that ArbOS state).
• Profile the gas a prospective transaction would use without spending any ETH — handy given Arbitrum splits L2 execution cost from L1 calldata cost.
• Test proposed contract-logic changes against live Arbitrum One state using stateOverrides to inject modified bytecode.

Parameters

Response

Example request

1curl https://arbitrum.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 Arbitrum One playground.

Errors & troubleshooting

Common pitfalls

• The call runs against the block state you name, so a result can differ from real execution when the contract reads block-specific context (timestamp, base fee, block number) — set blockOverrides deliberately if that matters.
• Simulating against a historical Arbitrum One block needs an archive node; a pruned node only holds recent ArbOS state.
• For complex contracts the default struct logger can return very large output — use a compact tracer like callTracer or disable stack/memory/storage in the options.

Supported networks

• Mainnet — Chain ID: 42161
• Sepolia — Chain ID: 421614

See also

• debug_traceTransaction
• trace_call
• debug_storageRangeAt
• debug_traceBlockByNumber

1curl https://arbitrum.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",{}]}'