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

# Installing and Initializing the Vouch SDK in Your App

> Install vouch-sdk via npm, pnpm, or yarn, then initialize the client with your API key to access identity, fraud, and escrow in one place.

The Vouch SDK is a TypeScript-first package that gives your application access to identity verification, fraud assessment, and escrow primitives through a single unified client. Install it once, initialize it with your API key, and every module is available on the resulting instance.

## Install the package

<CodeGroup>
  ```bash npm theme={null}
  npm install vouch-sdk
  ```

  ```bash pnpm theme={null}
  pnpm add vouch-sdk
  ```

  ```bash yarn theme={null}
  yarn add vouch-sdk
  ```
</CodeGroup>

## Initialize the client

Import the `Vouch` class and construct a client with your developer API key. Store the instance somewhere your application can reuse it — a singleton module, a provider, or a dependency-injection container.

```typescript theme={null}
import Vouch from 'vouch-sdk';

const vouch = new Vouch('your-api-key');
```

You can also pass an `options` object to override the default API or modal URLs:

```typescript theme={null}
import Vouch from 'vouch-sdk';

const vouch = new Vouch('your-api-key', {
  apiUrl: 'https://my-proxy.example.com/v1',
  verifyUrl: 'https://my-custom-modal.example.com',
});
```

### Constructor parameters

<ParamField path="apiKey" type="string" required>
  Your developer API key, obtained from the Vouch dashboard. This key is sent with every SDK request to authenticate your application.
</ParamField>

<ParamField path="options.apiUrl" type="string">
  Override the backend API base URL. Defaults to `https://vouch-fmql.onrender.com/v1`. Use this when routing requests through a proxy or when working against a self-hosted Vouch instance.
</ParamField>

<ParamField path="options.verifyUrl" type="string">
  Override the URL of the hosted identity verification modal. Defaults to `https://vouch-modal.vercel.app`. Override this only if you are deploying your own modal instance.
</ParamField>

## Environment variables

The SDK automatically reads `VOUCH_API_URL` from the environment and uses it as the `apiUrl` if no explicit value is passed in `options`. Set this in your `.env` file or deployment environment to avoid hard-coding URLs:

```bash theme={null}
VOUCH_API_URL=https://my-proxy.example.com/v1
```

<Note>
  `VOUCH_API_URL` is only applied when `options.apiUrl` is not provided. An explicit constructor option always takes precedence.
</Note>

## ESM configuration

The Vouch SDK ships exclusively as ES modules. If you are using TypeScript in a Node.js project, make sure your `tsconfig.json` targets a compatible module system:

```json tsconfig.json theme={null}
{
  "compilerOptions": {
    "module": "NodeNext",
    "moduleResolution": "NodeNext",
    "target": "ES2020"
  }
}
```

For browser bundlers (Vite, webpack, Rollup) or Next.js projects, `"module": "ESNext"` is the typical setting and no extra configuration is needed.

<Warning>
  If you see `ERR_REQUIRE_ESM` at runtime, your project is attempting to `require()` an ES module. Switch your entry point to use `import` syntax, or set `"type": "module"` in your `package.json`.
</Warning>

## Import styles

Use the default import for the `Vouch` class, named imports for individual interfaces and utilities, or both together:

```typescript theme={null}
// Default import — the Vouch client class
import Vouch from 'vouch-sdk';

// Named imports — types and utilities
import type { VouchOptions, FraudAssessParams } from 'vouch-sdk';
import { getDeviceFingerprint } from 'vouch-sdk';

// Combined
import Vouch, { getDeviceFingerprint } from 'vouch-sdk';
import type { IdentityVerifyResult } from 'vouch-sdk';
```

<Tip>
  Keep a single shared `vouch` instance across your application rather than constructing a new one per request. The SDK is stateless with respect to individual calls, so one instance is safe to reuse in any context.
</Tip>