state_call

Invokes a runtime API function locally on the node and returns the SCALE-encoded result. Use this to access runtime helpers such as transaction fee estimation (TransactionPaymentApi_queryInfo) or credential verifiers without mutating state.

Parameters

Parameter	Type	Required	Description
method	string	Yes	Runtime API function identifier (e.g., TransactionPaymentApi_queryInfo).
data	string	Yes	Hex-encoded SCALE payload expected by the runtime API.
at	string	No	Block hash to execute the call against a historical state.

Returns

Field	Type	Description
result	string	Hex-encoded SCALE bytes returned by the runtime API.

Example (Transaction Fee Quote)

import { ApiPromise, WsProvider } from '@polkadot/api';
import { hexAddPrefix } from '@polkadot/util';

const provider = new WsProvider('wss://api-manta-atlantic-mainnet.n.dwellir.com/YOUR_API_KEY');
const api = await ApiPromise.create({ provider });

// Create a dummy balance transfer and scale-encode it
const call = api.tx.balances.transferKeepAlive('5E5d...Recipient', 1_000_000_000_000_000_000n);
const payload = call.toU8a();

const result = await api.rpc.state.call(
  'TransactionPaymentApi_queryInfo',
  hexAddPrefix(payload)
);

console.log('Fee info SCALE-encoded', result.toHex());

Raw JSON-RPC

{
  "jsonrpc": "2.0",
  "method": "state_call",
  "params": [
    "TransactionPaymentApi_queryInfo",
    "0x280402000b50cd548d8501"
  ],
  "id": 1
}

Usage Notes

• Always consult the runtime metadata to confirm the expected SCALE payload for the target API.
• Provide a finalized block hash through the optional third parameter when you require deterministic results for audits.
• Responses are SCALE-encoded; decode them with @polkadot/api or scale-codec utilities.

Related Methods

• state_getMetadata
• rpc_methods