trace_block

trace_block returns the OpenEthereum-style call-tree traces for every transaction in one Arbitrum One block, chosen by hex block number or a tag like latest. Each entry is a flat trace object with a transactionPosition tying it back to its transaction, so you can reconstruct all internal ETH transfers, calls, creates, and self-destructs in the block at once. Arbitrum One is a Nitro Optimistic Rollup (chain ID 42161) that meters gas in ETH and confirms quickly via its sequencer, which keeps block-level indexing busy. Send requests to https://arbitrum.therpc.io/YOUR_API_KEY.

Use cases

• Extract every internal transaction in an Arbitrum One block for an explorer index or analytics pipeline, including transfers that emit no event.
• Analyze MEV activity across all transactions in a specific block — sandwiching and arbitrage around Arbitrum DEXs like Uniswap and Camelot.
• Track ETH and value flows into and out of a contract for an entire block in a single call instead of tracing transactions one by one.

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": "trace_block",
7    "params": ["latest"],
8    "id": 1
9  }'

Try it live in the Arbitrum One playground.

Errors & troubleshooting

Common pitfalls

• It returns every trace for every transaction, so a high-throughput Arbitrum One block produces a very large response — page through history block by block.
• Requires a trace-enabled archive node; most public Arbitrum endpoints do not expose the trace namespace at all.
• Avoid pending for production data: Arbitrum's fast sequencer means a pending block can change before it settles, and final L2 ordering follows the L1 challenge window.

Supported networks

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

See also

• trace_transaction
• trace_filter
• trace_replayBlockTransactions
• 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":"trace_block","params":["latest"]}'