Understand the default Hosting site

A Firebase project's default Firebase Hosting site is the primary Hosting site for the project.

It's associated with the following two Firebase-provisioned default subdomains:

  • DEFAULT_SITE_ID.web.app
  • DEFAULT_SITE_ID.firebaseapp.com.

These subdomains serve the web app content that you deploy to Firebase Hosting and have access to all of the Firebase project's resources (such as databases, storage, and authentication).

Your project's default Hosting site is also used by other Firebase tools and services, for example:

  • It serves as the default target for Firebase CLI deployments (unless you configure deploy targets).
  • Its *.firebaseapp.com subdomain is used as the default authDomain in your Firebase Web App configuration for Firebase Authentication flows (such as Google Sign-In).

On this page, learn more about the default Hosting site:

Create a default Hosting site

The way that your default Hosting site is created depends on when you created your Firebase project.

Before October 15, 2026

If you created your Firebase project or added Firebase to an existing Google Cloud project before October 15, 2026, then your project's default Hosting site was automatically created for you at that time.

After October 15, 2026

If you created your Firebase project or added Firebase to an existing Google Cloud project after October 15, 2026, then your project's default Hosting site is created on demand.

The first Hosting site created in your Firebase project always becomes your default Hosting site.

If your Firebase project does not yet have a default Hosting site and you do any of the following for the first time in your Firebase project, a default Hosting site will be created.

Explicitly create the default Hosting site

When you do any of the following, Firebase creates the default Hosting site with the requested site ID:

Implicitly create the default Hosting site

  • When you do any of the following, Firebase asks you to create the default Hosting site yourself (or asks for a preferred site ID to create the site for you):

    • Console: Create a Firebase Web App using the Firebase console "add app" workflow
    • CLI: Run firebase init hosting
    • CLI: Run firebase init and select hosting
    • CLI: Run firebase init auth
    • CLI: Run firebase init and select authentication
    • CLI: Run firebase deploy --only hosting
    • CLI: Run firebase deploy with hosting configured in your firebase.json
    • CLI: Run firebase apps:create web

  • When you do any of the following, Firebase automatically creates the default Hosting site for you in the background (and does not ask for a preferred site ID) for any of the following Firebase Authentication related scenarios:

    • Console: Enable Firebase Authentication
    • Enable the identitytoolkit.googleapis.com API via the gcloud CLI, REST, Terraform, etc.

Find the default Hosting site domain

You can find your project's default Hosting site domain in the Firebase configuration for your Firebase Web App (the authDomain field) or by directly querying Firebase Hosting for the default site. If there is no authDomain field or DEFAULT_SITE site, learn about creating a default Hosting site.

  • Firebase console (Project settings):

    1. In the Firebase console, go to the Settings > General tab.
    2. In the Your apps card, select any Firebase Web App.
    3. Select Config to view the app's Firebase configuration.
    4. The domain for your default Hosting site is listed in the authDomain field.

  • Firebase CLI:

    1. From any directory, run the following command with your project ID:

      firebase apps:sdkconfig web --project PROJECT_ID

    2. If prompted, select any Firebase Web App to print the app's Firebase configuration.

    3. The domain for your default Hosting site is listed in the authDomain field.

  • Hosting REST API:

    1. Call the projects.sites.list endpoint with your project ID.
    2. Your default Hosting site is labeled as "type": "DEFAULT_SITE" and its domain is in the defaultUrl field.

  • Your web app's codebase:

    In a web app that's set up to use Firebase, you can find your project's default Hosting site in your Firebase configuration in the authDomain field.

Determine the site ID for the default Hosting site

After October 15, 2026, here's how the site ID for the default Hosting site will be determined:

  • If you create the default Hosting site yourself (or you're asked for a preferred site ID), then you can use any available site ID. We recommend trying to use your project ID.

  • If Firebase automatically creates the default Hosting site for you without asking for a preferred site ID, then we'll try to use the project ID as the site ID. However, if that value is already taken, then we'll append 5 random characters to the project ID.

    Note that this was the way that Firebase created the default Hosting site ID before October 15, 2026.

Learn more about the situation where your default Hosting site does not use your project ID.

FAQ and troubleshooting

The following are answers to frequently asked questions (FAQs) and troubleshooting information about the default Hosting site.

Cannot change or delete the default Hosting site

After the default Hosting site is created for your project, you can't change it or delete it.

If you want a site with a different site ID and Firebase-provisioned subdomains (SITE_ID.firebaseapp.com and SITE_ID.web.app), then you can create an additional site using the multisites feature of Firebase Hosting.

Default Hosting site not using project ID

When Firebase automatically creates your project's default Hosting site (and does not ask for your preferred site ID), we try to use your project ID for the site ID.

However, because Firebase has no way to anticipate and thus reserve all the possible project IDs that might be created one day, someone else might have already created a site in their project that uses your project ID as a site ID. This situation can happen if your project ID is something relatively common or popular. For example, if your project ID is something like logs-dashboard, then someone very likely already used that ID as one of their site IDs.

In this situation, we can't use your project ID for your project's default Hosting site. Instead, we append 5 random characters to your project ID for your default Hosting site.

Error about not having a default Hosting site

To fix this kind of error, you need to create a default Hosting site for your Firebase project.

Details of why you might get this error

Starting October 15, 2026, Firebase no longer creates a default Firebase Hosting site when you create a Firebase project or add Firebase to an existing Google Cloud project.

Instead, Firebase only creates the default Hosting site in the following scenarios:

  • (Explicitly) If the default Hosting site is explicitly created (for example, by calling the projects.sites.create endpoint).

  • (Implicitly) If an action taken on the Firebase project might require a default Hosting site (for example, by clicking through the Firebase Hosting get started flow in the Firebase console or enabling Firebase Authentication).

To accommodate this change, if your Firebase project doesn't yet have a default Hosting site, Firebase will almost always prompt you to create one:

  • In most situations, Firebase asks for your preferred site ID and then automatically creates the default Hosting site for you.
  • In a few situations, Firebase asks you to create the default Hosting site yourself and provides you with options to do that (for example, by running a CLI command).

Unfortunately, in some situations, we can't accommodate this change and you may get a generic error about not having a default Hosting site. To fix this kind of generic error, use one of the options described in creating a default Hosting site.


Changes for deferred creation of the default Hosting site

This section describes the changes for the deferred creation of a Firebase project's default Firebase Hosting site. These changes take effect starting October 15, 2026.

  • The default Hosting site is not created when a new Firebase project is created or Firebase is added to an existing Google Cloud project.

  • Firebase only creates the default Hosting site in the following scenarios:

    • (Explicitly) If the default Hosting site is explicitly created (for example, by calling the projects.sites.create endpoint).

    • (Implicitly) If an action taken on the Firebase project might require a default Hosting site (for example, by clicking through the Firebase Hosting get started flow in the Firebase console or enabling Firebase Authentication).

With these changes, here are some important topics to understand: