chain_getBlockHash

Description

Returns the block hash for a given block number. Without parameters, it returns the hash of the latest block. This is useful when you store block numbers but need hashes to query storage or block data.

Parameters

Parameter	Type	Required	Description
blockNumber	string | number	No	Hex-encoded or decimal block number. If omitted, the latest block hash is returned

Returns

Field	Type	Description
result	string	Hex-encoded block hash

Request Example

{
  "jsonrpc": "2.0",
  "method": "chain_getBlockHash",
  "params": [9453714],
  "id": 1
}

Response Example

{
  "jsonrpc": "2.0",
  "result": "0xd4b3a0e3b88b7c25215926bbf7c733f5c31e69c0c8c4b4a86d6ec3f3f086e95d",
  "id": 1
}

Code Examples

JavaScript

const hash = await api.rpc.chain.getBlockHash(9053714n);
console.log('Block hash:', hash.toHex());

Python

payload = {
    "jsonrpc": "2.0",
    "method": "chain_getBlockHash",
    "params": ["0x9055f2"],
    "id": 1
}

resp = requests.post(
    "https://api-bifrost-polkadot.n.dwellir.com/YOUR_API_KEY",
    headers={"Content-Type": "application/json"},
    data=json.dumps(payload)
)
print(resp.json()["result"])

Rust

let hash = api.rpc().block_hash(Some(9_053_714u32.into())).await?;
println!("Block hash: {}", hash.expect("hash"));

Tips

• Use chain_getFinalizedHead to obtain the latest finalized hash, then feed that hash into chain_getBlock for deterministic data.
• When interacting with storage, always pin queries to a specific block hash to avoid race conditions during runtime upgrades.