Migration From Firebase


This document will help you migrate off of Firebase Authentication. If you are looking to compare FusionAuth and Firebase Authentication, this document may help.

This guide assumes you have installed FusionAuth. If you have not, please view our installation guides and install FusionAuth before you begin. For more general migration information, please view the FusionAuth migration guide.

There are a number of different ways applications can be integrated with Firebase, and it would be difficult to cover them all. This guide mentions the typical parts of a bulk migration and focuses on migrating user data from a Firebase managed user database into FusionAuth.

Planning Considerations

Obtaining User Data

You can use the Firebase CLI or API to export user data. This guide uses the CLI, but if you have a large number of users, or want to build the migration into your application, the API might be useful. Firebase also has a high level export guide worth reviewing.

If you haven’t already installed and set up the Firebase CLI, you can follow the guide here to do so.

Mapping User Attributes

The attributes of the User object in FusionAuth are well documented.

If there is an attribute in your user which cannot be directly mapped to a FusionAuth attribute, you can place it in the user.data field. This field can store arbitrary JSON values and will be indexed and searchable.

Social Logins

Firebase also provides integrations with other social login providers such as Twitter, Google or Facebook. Review the supported FusionAuth Identity Providers to ensure your social providers are supported.

If not supported explicitly, a provider may work with an OIDC or SAML connection. Otherwise, please open a feature request.

When migrating social logins, you may need to modify the switches of the Firebase import script. See Use the Script for more.

Migrating users with social logins such as Apple or Facebook requires that you have an existing user Id for that provider. What this unique user Id looks like depends on the particular social identity provider. The unique Id may be an email address, an integer, UUID, or a random string.

Configure the appropriate FusionAuth Identity Provider with the same values (client_id, etc) as the original user management system you are migrating away from.

Import users with the Import API, assigning each user with a social login a random password such as a UUID.

Your next step depends on whether the social login provider’s unique identifier is available as part of your migration data. If you have the social login provider’s unique identifier, for each user, use the Link API to create a link with the appropriate User Id, Identity Provider Id and Identity Provider User Id.

You do not need to migrate the social network token, which may or may not be accessible. During the first login of a newly migrated user, FusionAuth finds the unique user in the social login provider based on the migrated Identity Provider User Id, and completes the login. During this process, FusionAuth stores a token on the Link, if the social provider returns one. Depending on the configuration of the social provider, users may see a prompt asking if they want to allow FusionAuth to have access to user data such as email address.

IdP Linking Strategies are available since version 1.28.0. Before that version, users were linked on email.

If you do not have the social login provider’s identifier, you need to decide if you want to transparently link the two accounts, which is easier for the end user, or if you want to ask the user to manually link the accounts, which is more accurate, but may be confusing.

To transparently link the accounts, choose a linking strategy of Link On Email or Link On Username, which will create the user if they don’t exist. However, if the user has an email address at their social provider which differs from the email address that was used to sign up for your application and which you imported to FusionAuth, then two accounts will be created.

For example, if the user has a Google account richard@gmail.com, but signed up for your application with richard@fusionauth.io, then if you use the Link On Email strategy, two different accounts will be created, since FusionAuth is trying to match on email address and they don’t. The same holds true for usernames with the Link on Username strategy.

To prompt the user to link the accounts, choose a linking strategy of Pending, which will prompt the end user to sign into FusionAuth after they sign into the social provider, authoritatively linking the two accounts.

Here’s more information about IdP Linking Strategies.

Other Entities

There are often other important entities, such as connections or roles, that need to be migrated. There are usually fewer of these, so an automated migration may not make sense, but plan to move this configuration somehow.

Be aware that functionality may not be the same between and FusionAuth. This is different from user data; as long as you can somehow migrate a login identifier (a username or email) and a password hash, a user will be authenticated and successfully migrated. You can download FusionAuth before you begin a migration and build a proof of concept to learn more about the differences.

A partial list of what may need to be migrated for your application to work properly includes the following:

In FusionAuth, users are explicitly mapped to applications with a Registration.

In Firebase, users have access to all Firebase Applications in the same project by default. You can control access by using Roles and Security Rules per Application if you need.


When creating an object with the FusionAuth API, you can specify the Id. It must be a UUID.

This works for users, applications, and tenants, among others.

Firebase uses a custom UID format. When migrating, a new UUID will be created for the user on FusionAuth.

If you have external dependencies on an Id stored in Firebase, you can add a new attribute under user.data (such as user.data.originalId) with the value of the Firebase Id. Because everything under user.data is indexed and available via search, you’ll be able to find your users using either the new FusionAuth Id, or the original Firebase one.

Login UI

Firebase has pre-built UIs for web, iOS, Android, etc. called FirebaseUI Auth. You can also choose to build your own login page, and call the Firebase APIs.

FusionAuth’s login experience is similar. You can choose to build your own login pages or use FusionAuth’s hosted login pages. Read more about these choices.

Once you’ve planned your migration, the next step is to export your user data from Firebase.

Exporting Users

To export users with the Firebase CLI, you’ll perform the following steps:

  1. Install the Firebase CLI
  2. Retrieve the Project Id of the Firebase application you want to export the users from
  3. Download the exported file in your chosen format

Install the Firebase CLI

Navigate to the https://firebase.google.com/docs/cli#install-cli-mac-linux[Firebase CLI documentation], and install the Firebase CLI to your system.

After installing the CLI, be sure to login and test that the installation is successful.

Retrieve the Project Id

Before exporting the users, you’ll need the Project ID of the Firebase project you want to export from. To get this ID, run the following Firebase CLI command:

firebase projects:list

This will list all your Firebase projects, like this:

List of Firebase projects

│ Project Display Name │ Project ID   │ Project Number │ Resource Location ID │
│ fusion               │ fusion-bea44 │ 1021914842301  │ [Not specified]   

Make a note of the Project Id of the Firebase project you want to export from.

Download the File

To download the user file, run the following https://firebase.google.com/docs/cli/auth[Firebase auth:export CLI command]:

firebase auth:export users.json --format=JSON --project your_project_id

Replace your_project_id with the Project Id you noted above.

After the export finishes, you’ll end up with a JSON file called users.json. It should look something like this:

{"users": [
      "localId": "OzDdXA7LwoR7lX2MH7AXaEmmn5u2",
      "email": "user1@test.com",
      "emailVerified": false,
      "passwordHash": "0fn2PA6FmYZynpk9cvekSgbJTXa7j0XQAwtp4XuyyuIYzX5hASd4mB4GFeaS5OiG9mENrvt+sPoZmwVjvEDZ2Q==",
      "salt": "+mkMRRbwdwqJkA==",
      "createdAt": "1648020042135",
      "disabled": false,
      "providerUserInfo": []
      "localId": "bBd018SFAYa8fkkZdgAz3PEgaKj1",
      "email": "user2@test.com",
      "emailVerified": false,
      "passwordHash": "TFJtUjKMN4dNcp5IuSwaeRkPwjwpkp9ZlqXuL/QHsQ3097QLHnZWccWt2yThLa0Q5rmbuOOXoqzoHBZM8x3GpQ==",
      "salt": "RHQ5jbaxNJ1lDA==",
      "createdAt": "1648020072141",
      "disabled": false,
      "providerUserInfo": []

Importing Users

Next up, import the user data. Here are the steps we need to take.

  1. Set Up FusionAuth
  2. Add the scrypt Hashing Plugin
  3. Get the Script
  4. Install Needed Gems
  5. Use the Script
  6. Verify the Import
  7. The Final Destination of Imported Users

Set Up FusionAuth

You need to set up FusionAuth so migrated user data can be stored. As mentioned above, this guide assumes you have FusionAuth installed.

If you don’t, view our installation guides and install it before proceeding further.

Create a Test Tenant

It is best to create a separate tenant for migration testing. Tenants logically isolate configuration settings and users. If a migration goes awry or you need to redo it after tweaking settings, you can delete the test tenant and start with a clean system. To add a tenant, navigate to Tenants and choose the Add button (green plus sign).

Adding a tenant.

Give it a descriptive Name like Firebase import test. You shouldn’t need to modify any of the other configuration options to test importing users.

Save the tenant.

The tenant creation screen.

Record the Id of the tenant, which will be a UUID. It will look something like 25c9d123-8a79-4edd-9f76-8dd9c806b0f3. You’ll use this later.

The tenant list.

Create a Test Application

Applications are anything a user can log in to. In FusionAuth there’s no differentiation between web applications, SaaS applications, APIs and native apps. To add an application, navigate to Applications and click on the Add button (the green plus sign). Give the application a descriptive name like Firebase application.

Select your new tenant, created above, in the dropdown for the Tenant field.

Navigate to the OAuth tab and add an entry to Authorized redirect URLs. Use a dummy value such as https://example.com. Later, you’ll need to update this to be a valid redirect URL that can take the authorization code and exchange it for a token. Learn more about this in the FusionAuth OAuth documentation.

You shouldn’t need to modify any of the other configuration options to test importing users. Save the application.

The application creation screen.

Next, view the application by clicking the green magnifying glass and note the OAuth IdP login URL. You’ll be using it to test that users can log in.

Finding the login URL.

Add an API Key

The next step is to create an API key. This will be used by the import script. To do so, navigate to Settings -> API Keys in the administrative user interface.

Adding an API key

This key needs to have the permission to run a bulk import of users. In the spirit of the principle of least privilege, give it only the following permissions:

Record the API key string, as you’ll use it below.

Setting API key permissions

Add the scrypt Hashing Plugin

Most Firebase projects use a https://github.com/firebase/scrypt[modified version of the scrypt algorithm] for password hashes. FusionAuth does not support scrypt directly, but does support plugins for custom hashing.

To extend FusionAuth to support scrypt, follow the instructions for cloning, building and installing the plugins example repository. Before building the project, navigate to the src/main/java/com/mycompany/fusionauth/plugins/ExampleFirebaseScryptPasswordEncryptor.java file to add in a few scrypt parameters, which we’ll get from Firebase.

In Firebase, navigate to the Authentication panel, and click on the three dots near the Add User button. Then select Password hash parameters. This will open a modal with the parameters we need. Make a note of them.

Now open the src/main/java/com/mycompany/fusionauth/plugins/ExampleFirebaseScryptPasswordEncryptor.java file. Copy the Firebase parameters from above into the variables under the Firebase Scrypt Parameters comment.

Adding the scrypt parameters to the plugin

  /* Firebase Scrypt Parameters. You can find the correct settings for your Firebase project 
    by opening the Firebase console, navigating to the Authentication panel, and clicking
    on the 3 dots near the the **Add User** button. Then select **Password hash parameters**.
    This will open a modal with the parameters needed below. Copy them here */
  private static final int memcost = 14;
  private static final int rounds = 8;
  private static final String saltSep = "Bw==";
  private static final String base64_signer_key = "GhlZmw+EylyJl3fhsIOa+bmAEP1sYSHfZargl1unu/5mCp7pi818imxZOdSjM1558T+XU3cBflyr5HDghZqv7Q==";

After you have copied over the parameters, build and install the plugin project as detailed in the plugins guide. You may need to change the test case parameters in the file src/test/java/com/mycompany/fusionauth/plugins/ExampleFirebaseScryptPasswordEncryptorTest.java to match a known password, salt and hash from your Firebase installation.

After installing the plugin, and restarting FusionAuth, navigate to the Test Tenant you created earlier. Click the edit icon. Under the Password tab, find the section Cryptographic hash settings. Choose example-salted-firebase-scrypt as the Scheme.

Set hash scheme

If that plugin doesn’t show up, please review the plugin troubleshooting steps.

Get the Script

FusionAuth provides an import script under a permissive open source license. It requires ruby (tested with ruby 2.7). To get the script, clone the git repository:

Getting the import scripts

git clone https://github.com/FusionAuth/fusionauth-import-scripts

Navigate to the directory:

cd fusionauth-import-scripts/undefined

Install Needed Gems

The following gems must be available to the import script:

Most likely all of these will be on your system already, except the fusionauth_client gem.

If you have bundler installed, run bundle install in the firebase directory. Otherwise install the needed gems in some other way.

Use the Script

You can see the output of the script by running it with the -h option:

Running the import script with the help command line switch

ruby ./import.rb -h

The output will be similar to this:

The help output of the import.rb script

Usage: import.rb [options]
    -l, --link-social-accounts       Link social accounts, if present, after import. This operation is slower than an import.
    -r APPLICATION_IDS,              A comma separated list of existing applications Ids. All users will be registered for these applications.
    -o, --only-link-social-accounts  Link social accounts with no import.
    -u, --users-file USERS_FILE      The exported JSON user data file from Firebase. Defaults to users.json.
    -f FUSIONAUTH_URL,               The location of the FusionAuth instance. Defaults to http://localhost:9011.
    -k, --fusionauth-api-key API_KEY The FusionAuth API key.
    -t TENANT_ID,                    The FusionAuth tenant id. Required if more than one tenant exists.
    -m, --map-firebase-id            Whether to map the Firebase id for normal imported users to the FusionAuth user id.
    -h, --help                       Prints this help.

For this script to work correctly, set the following switches, unless the defaults work for you:

The -o and -l switches will attempt to create links for any social users (where the user authenticated via Google or another social provider) found in the users data file.

If you are loading social users, you must create the social providers in FusionAuth beforehand, or the links will fail. Additionally, creating a link is not currently optimized in the same way that loading users is. So it may make sense to import all the users in one pass (omitting the -l switch). Then, after the users are imported, create the links using the -o switch in a second pass.

The social account linking functionality will only work with FusionAuth versions above or equal to 1.28. The fusionauth_client library must be >= 1.28 as well.

You may or may not want to use the -m switch, which takes the Firebase Id for users without a social login and uses the same value for the FusionAuth user Id. If you have external systems reliant on the Firebase user identifier, set this. Doing so ensures imported users have the same Id as they did in Firebase. Otherwise, you can omit this switch.

When you run the script, you’ll see output like:

Import script output

$ ruby ./import.rb -f http://localhost:9011 -k '...' -u user-data.json
FusionAuth Importer : Firebase
 > User file: user-data.json
 > Call FusionAuth to import users
 > Import success
Duplicate users 0
Import complete. 2 users imported.

Enhancing the Script

You may also want to migrate additional data. Currently, the following attributes are migrated:

The migrated user will have the Firebase project Id and original user Id stored on the user.data object. If you have additional user attributes to migrate, review and modify the map_user method.

You may also want to assign Roles, or associate users with Groups, by creating the appropriate JSON data structures in the import call. These are documented in the Import User API docs. This will require modifying the import.rb code.

Verify the Import

Next, log in to the FusionAuth administrative user interface. Review the user entries to ensure the data was correctly imported.

List imported users.

You can manage the user by clicking on the Manage button (black button) to the right of the Created date in the list to review the details of the imported user’s profile.

If you have a test user whose password you know, open an incognito window and log in to ensure the hash migration was successful. You recorded the URL to log in to the example application in Create a Test Application.

The user login screen.

After the test login, the user will be redirected to a URL like https://example.com/?code=FlZF97WIYLNxt4SGD_22qvpRh4fZ6kg_N89ZbBAy1E4&locale=fr&userState=Authenticated. This happens because you haven't set up a web application to handle the authorization code redirect.

That is an important next step but is beyond the scope of this document. Consult the 5 minute setup guide

for an example of how to do this.

The Final Destination of Imported Users

After you are done testing, you can choose to import users into the default tenant or a new tenant. Whichever you choose, make sure to update the -t switch to the correct value before running the import for the final time.

If you aren’t keeping users in the test tenant, delete it.

If you need to start over because the import failed or you need to tweak a setting, delete the tenant you created. This will remove all the users and other configurations for this tenant, giving you a fresh start. To do so, navigate to Tenants and choose the Delete button (red trash can icon).

Deleting a tenant.

Confirm your desire to delete the tenant. Depending on how many users you have imported, this may take some time.

What to Do Next

You now have your users migrated, or a plan to do so. Congratulations! What is next?

You need to migrate additional configurations, as mentioned in Other Entities. Since the type of configuration varies, it is hard to provide a full list of how to import these items, but the general pattern will be:

Make sure you assign your users to the appropriate FusionAuth applications. You can do this either:

You’ll also need to modify and test each of your applications, whether custom, open source, or commercial, to ensure:

If your application uses a standard OAuth, SAML or OIDC library to communicate with , the transition should be relatively painless.

Additional Support

If you need support in your migration beyond that provided in this guide, you may: