eth_getBlockByNumber

eth_getBlockByNumber returns the full block data for an Arbitrum One L2 block at a given height or named tag (latest, finalized, safe, earliest, pending). On this ETH-gas Optimistic Rollup it is the standard way to walk the chain or pull the current tip, since the Nitro sequencer is producing blocks sub-second. Send the request, with a boolean for full transactions versus hashes, to https://arbitrum.therpc.io/YOUR_API_KEY (chain ID 42161).

Use cases

• Walk Arbitrum One forward block-by-block in an indexer, keeping pace with the fast Nitro block cadence.
• Fetch the latest block for a real-time monitoring dashboard of L2 activity.
• Retrieve the finalized block to anchor reorg-safe queries — important on a rollup where soft confirmations precede L1-backed finality.
• Pull all transaction hashes from a block (with includeTransactions=false) before fetching their receipts in bulk.

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

Try it live in the Arbitrum One playground.

Errors & troubleshooting

Common pitfalls

• Pass a real boolean for includeTransactions, not the string "true" — the node requires the JSON boolean type.
• When you need every receipt in a block, prefer a single eth_getBlockReceipts call over N separate eth_getTransactionReceipt calls.
• With includeTransactions=true, a heavily loaded Arbitrum One block can reach 1–2 MB given the rollup's high transaction throughput — budget bandwidth accordingly.

Supported networks

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

See also

• eth_getBlockByHash
• eth_getBlockReceipts
• eth_blockNumber
• eth_getBlockTransactionCountByNumber

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":"eth_getBlockByNumber","params":["latest",false]}'