eth_syncing

eth_syncing reports the current sync status of an OP Mainnet node — the OP Stack rollup that settles to Ethereum L1 and uses ETH for gas. It returns false when the node is fully caught up to the chain head, or an object with startingBlock, currentBlock, and highestBlock while it is still importing blocks. Because OP Mainnet produces blocks roughly every 2 seconds, a node falling behind shows up quickly in the gap between currentBlock and highestBlock. Point the call at https://optimism.therpc.io/YOUR_API_KEY (chain ID 10, 0xa) to check whether the endpoint is ready to serve consistent reads.

Use cases

• Verify a freshly started OP Mainnet node has finished syncing before adding it behind a load balancer or routing user traffic to it.
• Render a sync-progress percentage in an infrastructure dashboard by comparing currentBlock against highestBlock.
• Gate application or indexer startup on a false return so you never query stale state during bootstrap.
• Diagnose a stuck or lagging node by polling currentBlock over time — on a ~2-second chain, a value that barely advances signals a problem.

Parameters

This method takes no parameters. Pass an empty array [].

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

Try it live in the Optimism playground.

Errors & troubleshooting

Common pitfalls

• Some clients can return false during certain sync phases even when the node is not fully usable, so do not treat false as an absolute guarantee — cross-check against a known recent block number when readiness is critical.
• On OP Stack this reports execution-layer (op-geth) sync only; the consensus/derivation layer (op-node) tracks L1 separately, so a node can report execution sync done while still deriving from L1.
• The object shape varies by client — Geth-style and Erigon-style responses include different extra counters — so code that reads optional fields should handle missing keys gracefully rather than assume a fixed schema.

Supported networks

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

See also

• eth_blockNumber
• eth_chainId
• net_peerCount

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":"eth_syncing","params":[]}'