# Sign Typed Data

> Documentation index: [llms.txt](https://namera.ai/llms.txt).

Source: https://namera.ai/docs/sdk/guides/signing/sign-typed-data

Sign structured EIP-712 data with your account.

Use `namera.sign()` with `type: "typed-data"` for EIP-712 payloads. The domain,
types, primary type, and message together define what is signed.

## Before You Start [#before-you-start]

Use an [authenticated client](https://namera.ai/docs/sdk/authentication) and a session key
installed on **Base Sepolia** with signature authority. Its API signature
policy must allow `typed-data` and match any configured domain rules.

```sh
npm install @namera-ai/sdk
```

## Define the Payload [#define-the-payload]

This example signs a `Greeting` for your application. Replace the verifying
contract with your application's contract on Base Sepolia, and use the domain
and types expected by that application.

```ts title="index.ts"
import { NameraClient, type EvmTypedData } from "@namera-ai/sdk";

const namera = new NameraClient({ apiKey: process.env.NAMERA_API_KEY! });

const typedData = {
  domain: {
    name: "Namera Example",
    version: "1",
    chainId: 84532,
    verifyingContract: "0x3333333333333333333333333333333333333333",
  },
  types: {
    Greeting: [{ name: "contents", type: "string" }],
  },
  primaryType: "Greeting",
  message: { contents: "Hello from Namera" },
} satisfies EvmTypedData;
```

The domain uses the numeric chain ID `84532`. The SDK request uses the network
identifier `eip155:84532`.

## Sign the Payload [#sign-the-payload]

Replace the account and session-key IDs with your own:

```ts title="index.ts"
const signed = await namera.sign({
  namespace: "eip155",
  walletId: "0199dfe1-0000-7000-8000-000000000001",
  sessionKeyId: "0199dfe1-0000-7000-8000-000000000002",
  chainId: "eip155:84532",
  type: "typed-data",
  typedData,
});

if (!signed.success) throw new Error(signed.error.message);

console.log(signed.data);
```

<div className="docs-response">

```json
{
  "namespace": "eip155",
  "walletId": "0199dfe1-0000-7000-8000-000000000001",
  "chainId": "eip155:84532",
  "account": "0x1111111111111111111111111111111111111111",
  "signature": "0x0000000100222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222221b",
  "type": "typed-data"
}
```

</div>

The signature above is illustrative. Keep the actual signature and the exact
payload you signed for [verification](https://namera.ai/docs/sdk/guides/signing/verify-signatures).

## Use Integer Values [#use-integer-values]

Typed-data messages must be JSON-compatible. For large integer fields such as
`uint256`, use decimal strings rather than JavaScript `bigint` values or
numbers that lose precision. This differs from transaction `value`, which
accepts a `bigint`.

## Match Your Signature Policy [#match-your-signature-policy]

When your session has typed-data rules, one rule must match the chain,
verifying contract, primary type, and any configured domain name and version.
Domain names and versions are case-sensitive.

These rules restrict the payload's domain and type, not the amounts inside a
permit or other authorization. Review the actual message before signing.

Signing returns a signature; it does not submit the payload to the target contract.