> ## Documentation Index
> Fetch the complete documentation index at: https://docs.portalhq.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Feature flags

> Enable or disable specific SDK behaviors using feature flags when initializing Portal.

## Overview

Feature flags are set on the `featureFlags` option when you create a `Portal` instance. They control optional behavior such as signing performance and backup options. You do not need to change your signing or wallet code when enabling flags—the SDK adapts automatically.

## Enabling feature flags

Pass `featureFlags` in the Portal constructor:

```typescript theme={null}
import Portal from '@portal-hq/web'

const portal = new Portal({
  rpcConfig: {
    'eip155:1': 'https://mainnet.infura.io/v3/YOUR_KEY',
  },
  apiKey: 'YOUR_PORTAL_CLIENT_API_KEY',
  featureFlags: {
    usePresignatures: true,
  },
})
```

## Available flags

### `usePresignatures`

* **Type:** `boolean`
* **Default:** `false`
* **Description:** When enabled, the SDK uses **presignatures** to improve signing latency. You do not call any presignature APIs yourself; the SDK generates presignatures in the background and uses them automatically when you sign (e.g. via `portal.request()` or `portal.rawSign()`).

**What presignatures do**

Presignatures pre-compute part of the MPC signing protocol ahead of time. When the user triggers a sign (EVM transaction or raw sign), the SDK consumes one presignature if available and completes the signature faster. If no presignature is available, the SDK falls back to normal signing. Behavior is transparent to your app.

**When to enable**

Enable `usePresignatures` when you want lower latency on EVM signing without changing your integration. The SDK fills a small buffer after wallet creation or recovery and replenishes it as presignatures are used.

**Limitations**

* Applies only to **SECP256K1** (EVM) signing. Solana (ED25519) signing is unchanged.
* Presignatures are single-use; the SDK manages creation and consumption for you.

**Example**

```typescript theme={null}
const portal = new Portal({
  rpcConfig: { 'eip155:1': 'https://...' },
  apiKey: 'YOUR_API_KEY',
  featureFlags: {
    usePresignatures: true,
  },
})

// Signing uses presignatures automatically when available
const signature = await portal.request({
  chainId: 'eip155:1',
  method: 'personal_sign',
  params: [message, address],
})
```

***

## Reference

For all constructor options and the `featureFlags` property, see the [Web SDK Reference](/sdks/web/reference#feature-flags).