debug_traceBlockByNumber

debug_traceBlockByNumber replays every transaction in an OP Mainnet block — addressed by hex block number or a tag like latest — and returns an opcode-level execution trace for each. On OP Mainnet, the OP Stack rollup where ETH pays for gas and blocks arrive about every 2 seconds, this is the go-to way to inspect a whole block's execution without knowing each transaction hash. Send the request to https://optimism.therpc.io/YOUR_API_KEY (chain ID 10, 0xa) with the block number and an optional tracer config, and the node returns one trace per transaction in canonical order.

Use cases

• Trace all transactions in a known OP Mainnet block to audit every state transition in one request.
• Extract the complete call graph for an entire block for MEV research using callTracer, including every nested internal call.
• Compare the gas profiles of all transactions in a block to spot outliers — useful given OP Mainnet's L1 data-fee component on top of L2 execution gas.

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_traceBlockByNumber",
7    "params": [
8        "latest",
9        {}
10      ],
11    "id": 1
12  }'

Try it live in the Optimism playground.

Errors & troubleshooting

Common pitfalls

• A full-block trace replays every transaction; a busy OP Mainnet block can take a long time and return enormous responses, especially with the default struct-log tracer.
• Historical blocks require an archive node; a non-archive OP Mainnet node only holds recent state and will fail to replay older blocks.
• Tags like latest are valid but race with the chain — at ~2-second block times a new block may be produced mid-request, so pin a concrete number for reproducible results.

Supported networks

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

See also

• debug_traceBlockByHash
• debug_traceBlock
• debug_traceTransaction
• trace_block

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_traceBlockByNumber","params":["latest",{}]}'