> For the complete documentation index, see [llms.txt](https://docs.zama.org/protocol/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.zama.org/protocol/sdk/api-references/sdk/relayernode.md).

# 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()`](/protocol/sdk/api-references/sdk/relayerweb.md).

## Import

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

## Usage

```ts
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`.                          |

```ts
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](/protocol/sdk/api-references/sdk/relayerweb.md) — the browser variant, running FHE via bundled WASM
* [`cleartext()` transport](/protocol/sdk/api-references/sdk/relayercleartext.md) — the development variant, no FHE
* [ZamaSDK](/protocol/sdk/api-references/sdk/zamasdk.md) — pass the config to the SDK constructor
* [Node.js backend guide](/protocol/sdk/guides/node-js-backend.md) — server setup and per-request isolation
* [Configuration guide](/protocol/sdk/guides/configuration.md) — authentication and network presets


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://docs.zama.org/protocol/sdk/api-references/sdk/relayernode.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `build a script that syncs our docs to a CMS` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.