node() transport

Node.js relayer transport that runs FHE operations through @fhevm/sdk on the calling thread.

The node() transport factory configures a chain to run FHE operations in Node.js. It drives @fhevm/sdk directly on the calling thread — the server-side counterpart to web().

Import

import { node } from "@zama-fhe/sdk/node";

Usage

import { createConfig } from "@zama-fhe/sdk/viem";
import { ZamaSDK } from "@zama-fhe/sdk";
import { node } from "@zama-fhe/sdk/node";
import { sepolia } from "@zama-fhe/sdk/chains";

const config = createConfig({
  // Sepolia testnet needs no relayer key; for the mainnet relayer add
  // `auth: { __type: "ApiKeyHeader", value: process.env.RELAYER_API_KEY }` to the chain.
  chains: [sepolia],
  publicClient,
  walletClient,
  relayers: { [sepolia.id]: node() },
});

const sdk = new ZamaSDK(config);

Parameters

node() accepts an optional options object: per-client tuning forwarded to @fhevm/sdk, plus request defaults applied to every relayer round-trip on this chain. Most apps omit it and call node() bare; parallelism and FHE-artifact caching are handled internally.

Option	Type	Default	Purpose
batchRpcCalls	boolean	false	Batch the client's on-chain version-resolution reads into one JSON-RPC request instead of issuing them individually.
fheEncryptionKey	FheEncryptionKeyBytes	none — fetched from the relayer's keyurl	A pre-fetched FHE public encryption key — the object fetchFheEncryptionKeyBytes() returns — to skip the ~50 MB fetch @fhevm/sdk otherwise performs during init.
moduleVersions	"auto" | { tfhe?; kms?; checkCompatibility? }	"auto"	Pin the TFHE/KMS WASM module versions instead of auto-resolving them from the chain's on-chain protocol version.
timeout	number (ms)	3_600_000 (1 hour)	Maximum time to wait for a relayer request — an input-proof generation or a decryption, including its retry/backoff loop, not a single HTTP call. A per-call timeout overrides this default.
debug	boolean	false	Emit verbose per-request trace logs for this chain's relayer round-trips to console.log — a raw diagnostic switch, separate from any logger passed to createConfig.

node({
  batchRpcCalls: true,
  fheEncryptionKey, // reuse a key fetched elsewhere
  moduleVersions: "auto",
  timeout: 60_000,
});

timeout bounds only the relayer request itself, not @fhevm/sdk's one-time per-client init phase (protocol-version resolution, the FHE key fetch, WASM module load), which runs before the first request and can hang independently of this value.

Return Type

NodeRelayerConfig — a relayer config object you assign per chain in createConfig({ relayers }). You do not construct or interact with it directly.

Related

• web() transport — the browser variant, running FHE via bundled WASM

• cleartext() transport — the development variant, no FHE

• ZamaSDK — pass the config to the SDK constructor

• Node.js backend guide — server setup and per-request isolation

• Configuration guide — authentication and network presets