You can use Firebase Authentication to let your users authenticate with
Firebase using their email addresses and passwords, and to manage your app's
password-based accounts.

### AI prompt for AI assistance


***For AI assistance, copy the prompt below into your
AI coding agent (like Antigravity, Claude Code, Codex, and Cursor).**
You can customize the prompt and iterate with your agent. Visit
[Firebase agent skills](https://firebase.google.com/docs/ai-assistance/agent-skills.md.txt)
for detailed installation info.*

```
Help me use Firebase in my app.
1. Make sure that **Firebase agent skills** are installed and updated. For Claude Code, Codex, or Cursor agents, help me install the Firebase plugin. For other agents, run `npx skills add firebase/agent-skills`.  Always try to use **Firebase agent skills** for Firebase-related tasks.
2. Help me set up and use Firebase Authentication with email and password authentication in my app.
```

## Before you begin

1. [Add Firebase to your JavaScript project](https://firebase.google.com/docs/web/setup.md.txt).
2. If you haven't yet connected your app to your Firebase project, do so from the [Firebase console](https://console.firebase.google.com/).
3. Enable Email/Password as a sign-in provider for your Firebase project:
   1. In the Firebase console, go to **Security** \> [**Authentication**](https://console.firebase.google.com/project/_/authentication/).
   2. In the **Sign-in method** tab, enable the **Email/password** sign-in provider.
   3. Click **Save**.

   > [!NOTE]
   > **Tip:** If you prefer to use the [Firebase CLI](https://firebase.google.com/docs/cli.md.txt), run `firebase init auth` to configure authentication providers, and then run `firebase deploy --only auth` to deploy the changes to your project.

## Create a password-based account

To create a new user account with a password, complete the following steps in
your app's sign-up page:

1. When a new user signs up using your app's sign-up form, complete any new account validation steps that your app requires, such as verifying that the new account's password was correctly typed and meets your complexity requirements.
2. Create a new account by passing the new user's email address and password to `createUserWithEmailAndPassword`:

   ### Web

   ```javascript
   import { getAuth, createUserWithEmailAndPassword } from "firebase/auth";

   const auth = getAuth();
   createUserWithEmailAndPassword(auth, email, password)
     .then((userCredential) => {
       // Signed up 
       const user = userCredential.user;
       // ...
     })
     .catch((error) => {
       const errorCode = error.code;
       const errorMessage = error.message;
       // ..
     });
   ```

   ### Web

   ```javascript
   firebase.auth().createUserWithEmailAndPassword(email, password)
     .then((userCredential) => {
       // Signed in 
       var user = userCredential.user;
       // ...
     })
     .catch((error) => {
       var errorCode = error.code;
       var errorMessage = error.message;
       // ..
     });
   ```
   If the new account was created, the user is signed in automatically. Have a look at the Next steps section below to get the signed in user details.


   This is also where you can catch and handle errors. For a list of error codes have a look at the [Auth Reference Docs](https://firebase.google.com/docs/reference/js/auth.md.txt#autherrorcodes).

To protect your project from abuse, Firebase limits the number of new email/password and anonymous sign-ups that your application can have from the same IP address in a short period of time. You can request and schedule temporary changes to this quota from the Firebase console (go to the **Security** \> **Authentication** \> [**Sign-in method** tab](https://console.firebase.google.com/project/_/authentication/providers)).

## Sign in a user with an email address and password

The steps for signing in a user with a password are similar to the steps for
creating a new account. In your app's sign-in page, do the following:

1. When a user signs in to your app, pass the user's email address and password to `signInWithEmailAndPassword`:

   ### Web

   ```javascript
   import { getAuth, signInWithEmailAndPassword } from "firebase/auth";

   const auth = getAuth();
   signInWithEmailAndPassword(auth, email, password)
     .then((userCredential) => {
       // Signed in 
       const user = userCredential.user;
       // ...
     })
     .catch((error) => {
       const errorCode = error.code;
       const errorMessage = error.message;
     });
   ```

   ### Web

   ```javascript
   firebase.auth().signInWithEmailAndPassword(email, password)
     .then((userCredential) => {
       // Signed in
       var user = userCredential.user;
       // ...
     })
     .catch((error) => {
       var errorCode = error.code;
       var errorMessage = error.message;
     });
   ```
   Have a look at the Next steps section below to get the signed in user details.


   This is also where you can catch and handle errors. For a list of error codes have a look at the [Auth Reference Docs](https://firebase.google.com/docs/reference/js/auth.md.txt#autherrorcodes).

## Recommended: Set a password policy

[Video](https://www.youtube.com/watch?v=smB-4UogJpQ)

You can improve account security by enforcing password complexity requirements.

To configure a password policy for your project, open the **Password policy**
section in the **Security** \> **Authentication** \> **Settings** tab of the
Firebase console:

[Authentication Settings](https://console.firebase.google.com/project/_/authentication/settings)

Firebase Authentication password policies support the following password requirements:

- Lowercase character required

- Uppercase character required

- Numeric character required

- Non-alphanumeric character required

  The following characters satisfy the non-alphanumeric character requirement:
  `^ $ * . [ ] { } ( ) ? " ! @ # % & / \ , > < ' : ; | _ ~`
- Minimum password length (ranges from 6 to 30 characters; defaults to 6)

- Maximum password length (maximum length of 4096 characters)

You can enable password policy enforcement in two modes:

- **Require**: Attempts to sign up fail until the user updates to a password
  that complies with your policy.

- **Notify**: Users are allowed to sign up with a non-compliant password. When
  using this mode, you should check if the user's password complies with the
  policy on the client side and prompt the user in some way to update their
  password if it does not comply.

New users are always required to choose a password that complies with your
policy.

If you have active users, we recommend not enabling force upgrade on sign in
unless you intend to block access to users whose passwords don't comply with
your policy. Instead, use notify mode, which allows users to sign in with their
current passwords, and inform them of the requirements their password lacks.

### Validating a password on the client

```javascript
import { getAuth, validatePassword } from "firebase/auth";
```

```javascript
const status = await validatePassword(getAuth(), passwordFromUser);
if (!status.isValid) {
  // Password could not be validated. Use the status to show what
  // requirements are met and which are missing.

  // If a criterion is undefined, it is not required by policy. If the
  // criterion is defined but false, it is required but not fulfilled by
  // the given password. For example:
  const needsLowerCase = status.containsLowercaseLetter !== true;
}
```

## Recommended: Enable email enumeration protection

> [!NOTE]
> **Note:** If you created your project on or after September 15, 2023, email enumeration protection is enabled by default.

Some Firebase Authentication methods that take email addresses as parameters throw
specific errors if the email address is unregistered when it must be registered
(for example, when signing in with an email address and password), or registered
when it must be unused (for example, when changing a user's email address).
While this can be helpful for suggesting specific remedies to users, it can also
be abused by malicious actors to discover the email addresses registered by your
users.

To mitigate this risk, we recommend that you make sure
[email enumeration protection](https://cloud.google.com/identity-platform/docs/admin/email-enumeration-protection)
is enabled for your project. You can check this setting in the
Firebase console: go to the **Security** \> **Authentication** \>
[**Settings** tab](https://console.firebase.google.com/project/_/authentication/settings?useAutoProject=true),
and then click **User actions**.

Note that enabling this feature changes the error reporting behavior for
Firebase Authentication, so make sure your app doesn't rely on the more specific
errors.

## Next steps

After a user signs in for the first time, a new user account is created and
linked to the credentials---that is, the user name and password, phone
number, or auth provider information---the user signed in with. This new
account is stored as part of your Firebase project, and can be used to identify
a user across every app in your project, regardless of how the user signs in.

- In your apps, the recommended way to know the auth status of your user is to
  set an observer on the `Auth` object. You can then get the user's
  basic profile information from the `User` object. See
  [Manage Users](https://firebase.google.com/docs/auth/web/manage-users.md.txt).

- In your Firebase Realtime Database and Cloud Storage
  [Security Rules](https://firebase.google.com/docs/database/security/user-security), you can
  get the signed-in user's unique user ID from the `auth` variable,
  and use it to control what data a user can access.

You can allow users to sign in to your app using multiple authentication
providers by [linking auth provider credentials to an
existing user account.](https://firebase.google.com/docs/auth/web/account-linking)

To sign out a user, call [`signOut`](https://firebase.google.com/docs/reference/js/auth.md.txt#signout):

### Web

```javascript
import { getAuth, signOut } from "firebase/auth";

const auth = getAuth();
signOut(auth).then(() => {
  // Sign-out successful.
}).catch((error) => {
  // An error happened.
});
```

### Web

```javascript
firebase.auth().signOut().then(() => {
  // Sign-out successful.
}).catch((error) => {
  // An error happened.
});
```