voluptasmollitia/docs-exp/auth.auth.tenantid.md

Monorepo for the Firebase JavaScript SDK

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[Home](./index.md) &gt; [@firebase/auth](./auth.md) &gt; [Auth](./auth.auth.md) &gt; [tenantId](./auth.auth.tenantid.md)

## Auth.tenantId property

The Auth instance's tenant ID.

<b>Signature:</b>

```typescript
tenantId: string | null;
```

## Remarks

This is a readable/writable property. When you set the tenant ID of an Auth instance, all future sign-in/sign-up operations will pass this tenant ID and sign in or sign up users to the specified tenant project. When set to null, users are signed in to the parent project.

## Example


```javascript
// Set the tenant ID on Auth instance.
auth.tenantId = 'TENANT_PROJECT_ID';

// All future sign-in request now include tenant ID.
const result = await signInWithEmailAndPassword(auth, email, password);
// result.user.tenantId should be 'TENANT_PROJECT_ID'.

```