Firebase FAQ

How do I add Firebase to an existing Google project?

You may have existing projects managed through the Google Cloud console or the Google APIs console. By default, these projects are visible in the Firebase console, but are not considered to be Firebase projects.

To add Firebase to your existing project, click Add Project on the Firebase console landing page, then select your project in the Project name menu.

What is a Firebase project?

A project is a container for apps across iOS, Android and web. It supports sharing of features such as Database, Config and Notifications between your cross-platform apps.

You should add iOS, Android and web app variants to a single project. You can use multiple projects to support multiple environments, such as development, staging and production.

How many projects can I have per account?

• Free-tier Spark plan — Your project quota is limited to a small number of projects (usually around 5-10).
• Paid plans — Your project quota per billing account increases substantially as long as your Cloud billing account is in good standing.

The limit on project quota is rarely a concern for most developers, but if needed, you can request an increase in your project quota.

Note that the complete deletion of a project requires 30 days and counts toward your quota until it is fully deleted.

How many Firebase apps can I have in a project?

A project is a container for apps across iOS, Android and web. While there is no restriction on number of apps within a project, adding an app can create one or more underlying OAuth 2.0 client IDs. There is a limit of around 30 client IDs that can be created within a single project.

You should ensure that all apps within a project are platform variants of the same application from an end user perspective. For example, if you develop a white label application, each independently labelled app should have its own Firebase project.

Do I need to provide a SHA-1 when adding an Android app?

SHA-1 information is required by Firebase Authentication (when using Google signin or phone number signin) and Firebase Dynamic Links. If you're not using these features, you don't have to provide a SHA-1.

How do I resolve this error: "An OAuth2 client already exists for this package name and SHA-1 in another project"?

This error occurs if we detect that another Firebase or Google Cloud project contains an OAuth 2.0 client ID with the package name and SHA-1 that you specified. You can resolve this by following the instructions here.

How is my Firebase console language determined?

The language setting for the Firebase console is based on the language selected in your Google account settings. To change your language preference, see Change language.

The Firebase console is available in the following languages:

• English
• Brazilian Portuguese
• French
• German
• Indonesian
• Japanese
• Korean
• Russian
• Simplified Chinese
• Spanish
• Traditional Chinese

What roles and permissions does the Firebase console support?

The Firebase console and Google Cloud console use the same underlying roles and permissions. Learn more about roles and permissions in the Firebase IAM documentation.

Firebase supports the fundamental (primitive) roles of Owner, Editor, and Viewer:

• A project Owner can add other members to the project, set up integrations (project linking to services like BigQuery or Slack), and has full edit access for the project.
• A project Editor has full edit access for the project.
• A project Viewer has only read access for the project. Note that our UI currently does not hide/disable edit UI controls for project viewers, but these operations will fail for users with viewer role.

Firebase also supports:

• Firebase predefined roles — Curated Firebase-specific roles that enable more granular access control than the primative roles of owner, editor, and viewer.
• Custom roles — Fully customized IAM roles that you create to tailor a set of permissions that meet the specific requirements of your organization.

What are the prerequisites for linking Play/AdMob/AdWords/BigQuery to my Firebase project?

• For linking your Play account, you need to be both a Firebase project owner and a Play account owner.
• For linking your AdMob app, you need to be both a Firebase project owner and an AdMob administrator.
• For linking your AdWords account, you need to be both a Firebase project owner and an AdWords administrator.
• For linking your BigQuery project, you need to be the Firebase project owner.

What are the supported browsers for accessing Firebase console?

The Firebase console can be accessed from recent versions of popular desktop browsers such as Chrome, Firefox, Safari and Edge. Mobile browsers are currently not fully supported.

What open source notices should I include in my app?

On iOS, the Firebase pod contains a NOTICES file which includes the relevant entries. The Android SDK contains contains a helper activity for showing license information.

What versions of Xcode does Firebase support?

Firebase supports up to two major versions of Xcode, not including versions of Xcode that Apple no longer supports. For example, starting in March 2019, Apple requires at least iOS 12 on all iOS apps, meaning Xcode 9 support will be dropped and Xcode 10 will be the only major version supported.

Changes to support for specific minor or patch versions of Xcode (for example, 9.2.0 to 9.4.1) are determined based on the needs of the Firebase iOS SDK and a survey of developer usage. These changes are reflected in the Firebase iOS SDK release notes and on the Firebase iOS SDK setup page.

To see the minimum Xcode version supported by the Firebase iOS SDK, check the requirements listed in Add Firebase to your iOS Project.

Firebase support for Beta releases of Xcode is available on a "best effort" basis. Developers can track and submit issues in the Firebase iOS SDK repository on GitHub.

Which products are paid? Which are free?

Firebase's paid infrastructure products are the Realtime Database, Storage, functions, Hosting, Test Lab, and phone authentication. We offer a free tier for all of these features.

Firebase also has many free products: Analytics, Cloud Messaging, the Notifications composer, Remote Config, App Indexing, Dynamic Links, and Crash Reporting. You can use an unlimited amount of any of these products in all plans, including our free Spark plan. In addition, all Authentication features beyond phone authentication are free.

How do I know which plan is right for me?

Spark billing plan

Our Spark plan is a great place to develop your app for free, whether a hobby project or the next big start-up. You get all the free Firebase features (Analytics, the Notifications composer, Crash Reporting, and so on) and generous amounts of our paid infrastructure features. However, if you exceed your Spark plan resources in a calendar month, your app will be shut off for the remainder of that month. In addition, Google Cloud Platform features are not available in the Spark tier.

Flame billing plan

Our Flame plan is designed for early-stage startups and small- production apps looking for a predictable, low price but with more capacity than our free-tier offers for the Realtime Database, Storage, or Hosting resources. Like the Spark plan, Google Cloud Platform is not available on the Flame plan. Exceeding your plan resources in any month will cause your app to be shut off for the remainder of that month.

Blaze billing plan

Our Blaze plan is designed for large-scale production apps and apps that cannot accept downtime for exceeding plan limits. The Blaze plan also allows you to extend your app with paid Google Cloud Platform features. You pay only for the resources that you consume, allowing you to scale with demand. We strive to make our Blaze plan prices competitive with industry-leading cloud providers.

You can track your usage of Realtime Database and Hosting resources in the Firebase console. See Realtime Database Usage and Hosting Usage.

How can I monitor my usage and billing?

You can track your usage of project resources in the Firebase console on any of the following dashboards:

• Usage and billing dashboard
• Cloud Storage Usage dashboard
• Database Usage dashboard (both Cloud Firestore and Realtime Database)
• Hosting Usage dashboard

What happened to the Flame plan?

As of January 2020, the Flame billing plan ($25/mo of additional quota) is no longer available for new sign-ups.

• Existing Spark and Blaze plan projects and any new projects can no longer switch to or sign up for the Flame plan.
• If you move an existing Flame plan project to a different billing plan, the project cannot return to the Flame plan.
• Existing Flame plan projects can continue to use the Flame plan for now. However, you'll receive information in the coming months about the required timeline for moving to another billing plan.

Do you have more questions about the Flame plan retirement? Read some of the additional FAQs below.

Want to learn about the other billing plans offered by Firebase? Visit our Firebase pricing page! If you'd like to start moving any existing projects to another billing plan, you can do that in the Firebase console for your project.

Additional FAQs about the Flame plan retirement

How is the free usage in the Blaze plan different from the free usage in the Spark plan?

Free usage on the Blaze plan is calculated daily. Usage limits also differ from the Spark plan for Cloud Functions, phone authentication and Test Lab.

For Cloud Functions, free usage on the Blaze plan is calculated at the billing account level, not the project level and has the following limits:

• 2M invocations/month
• 400K GB-seconds/month
• 200K CPU-seconds/month
• 5 GB of networking egress/month

For phone authentication, free usage on the Blaze plan is calculated monthly.

For Test Lab, free usage on the Blaze plan has the following limits:

• 30 physical device minutes/day
• 60 virtual device minutes/day

Does the free usage quota reset when I change from a Spark to a Blaze plan?

Free usage from the Spark plan is included in the Blaze plan. Free usage does not reset when moving to a Blaze plan.

What is a "simultaneous database connection"?

A simultaneous connection is equivalent to one mobile device, browser tab, or server app connected to the database. Firebase imposes hard limits on the number of simultaneous connections to your app's database. These limits are in place to protect both Firebase and our users from abuse.

The Spark plan limit is 100 and cannot be raised. The Flame and Blaze plans have a limit of 200,000 simultaneous connections per database.

This limit isn't the same as the total number of users of your app, because your users don't all connect at once. If you need more than 200,000 simultaneous connections, please read Scale with Multiple Databases.

What happens if I exceed Spark or Flame plan storage or download limits for Realtime Database?

To provide you with a predictable price, the resources available to you in the Spark and Flame plans are capped. This means that when you exceed any plan limit in any month, your app will be turned off to prevent any further resource usage and additional charges.

What happens if I exceed Spark plan simultaneous connection limits for Realtime Database?

When your app reaches its concurrents limit on the Spark plan, any subsequent connections will be rejected until some of the existing connections are closed. The app will continue to work for users who are connected.

What happens if I exceed Spark or Flame plan upload, download or storage limits for Cloud Storage?

When you exceed limits for Cloud Storage in a project on the Spark or Flame plan, the result depends on the type of limit that you exceed:

• If you exceed the GB stored limit, you will not be able to store any more data in that project unless you remove some of the data stored or upgrade to a plan that provides more storage space, or unlimited storage space.
• If you exceed the GB downloaded limit, your app will not be able to download more data until the next day (starting at midnight, US Pacific Time), unless you upgrade to a plan with less restrictive limits, or with no limits.
• If you exceed the upload or download operations limit, your app will not be able to upload or download more data until the next day (starting at midnight, US Pacific Time), unless you upgrade to a plan with less restrictive limits, or with no limits.

How does Firebase's integration with Google Cloud Platform work?

Firebase is deeply integrated with Google Cloud Platform. Projects are shared between Firebase and Google Cloud Platform, so projects can have Firebase services and Google Cloud Platform services enabled. You can access the same project from the Firebase console or the Google Cloud Console. Specifically:

• Certain Firebase features are backed directly by Google Cloud Platform, such as Firebase Storage. The list of features backed by Google Cloud Platform will continue to grow over time.
• Many of your settings, including collaborators and billing information, are shared by Firebase and Google Cloud Platform. Your usage of both Firebase and Google Cloud Platform appears on the same bill.

In addition, when you upgrade to the Blaze plan, you can use any of Google Cloud Platform's world-class Infrastructure-as-a-Service and APIs directly inside your Firebase project, at standard Google Cloud Platform pricing. You can also export data from Google Analytics for Firebase directly to BigQuery for analysis. To learn more, see Link BigQuery with Firebase.

There are many security-enhancing, latency-improving, and time-saving benefits to using Google Cloud Platform with Firebase (versus other, cloud services that are not co-located). Check out the Google Cloud Platform site for more details.

What happens to my Firebase project if I add or remove billing accounts for that project in the Google Cloud Console?

If a billing account is added to a project in the Google Cloud Console, the same project will automatically be upgraded to the Firebase Blaze plan if that project is currently on the Spark or Flame plan.

In contrast, if an existing active billing account is removed from a project in the Google Cloud Console, that project will be downgraded to the Firebase Spark plan.

Can I upgrade, downgrade, or cancel at any time?

Yes, you can upgrade, downgrade, or cancel at any time. Note that we don't provide prorated refunds for downgrades or cancellations. This means that if you downgrade or cancel before the end of your billing period, you still pay for the remainder of the month.

What kind of support will I receive?

All Firebase apps, including free plans, come with email support from Firebase staff during US Pacific business hours. All accounts are limited to ten technical (troubleshooting) questions per year, but have unlimited support for billing-related issues, account-related issues, and incident reports.

Can I cap usage on the Blaze plan?

No, you cannot currently cap your Blaze plan usage. We are evaluating options for supporting caps on Blaze plan usage.

Blaze users can define a budget for their project or account, and receive alerts as their spending approaches those limits. For more information see Set Budget Alerts.

What are automated backups? Do you offer hourly backups?

Automated backups are an advanced feature for customers on our blaze plan that backs up your Firebase Realtime Database data once a day and uploads it to Google Cloud Storage.

We do not offer hourly backups.

Are Flame plan fees prorated if I sign up or downgrade partway through the month?

Yes for upgrades and no for downgrades. You can upgrade or downgrade at any time. Upgrades are prorated, and downgrades are not prorated. If you sign up for the Flame plan partway through the month, you will be charged only for the remainder of the month. However, if you downgrade partway through the month, you'll be charged for the remainder of the month (this is to prevent abuse).

Do you offer open-source, nonprofit, or educational discounts?

Our Spark and Flame plans can be used by any type of individual or organization, including nonprofits, schools, and open-source projects. Since these plans already include generous quotas, we don't offer any special discounts or plans for open-source, nonprofit, or educational projects.

Do you offer enterprise contracts, pricing, support, or dedicated infrastructure hosting?

Our Blaze plan is suitable for enterprises of all sizes, and our SLA meets or exceeds the industry standard for cloud infrastructure. However, we do not currently offer Enterprise contracts, pricing, or support, nor do we offer dedicated infrastructure hosting (that is, on-premises installations) for services like our Realtime Database. We are hard at work adding some of these features.

Do you offer ad-hoc pricing? I only want pay-as-you-go for one or two features.

We offer ad-hoc pricing in the Blaze plan, where you pay only for the features you use.

How do the paid Firebase plans work with Ads? Are there free advertising credits with paid plans?

The Firebase pricing plans are separate from Ads, so there are no free advertising credits. As a Firebase developer, you are able to "link" your Ads account to Firebase to support conversion tracking.

All ads campaigns are managed directly in Ads, and Ads billing is managed from the Ads Console.

Where can I find information about privacy and security in Firebase?

Check out the page Privacy and Security in Firebase.

Do the Firebase SDKs log any usage/diagnostic information outside of Analytics?

Yes. This is currently iOS-only, but may change in the future. The Firebase iOS SDK includes the FirebaseCoreDiagnostics framework by default. This framework is used by Firebase to collect SDK usage and diagnostics information to help prioritize future product enhancements. FirebaseCoreDiagnostics is optional, so if you would like to opt out of sending Firebase diagnostic logs, you can do so by unlinking the library from your application. You can browse the full source, including logged values, on GitHub

Why is Google Analytics a recommended part of using Firebase products?

Google Analytics is a free and unlimited analytics solution that works with Firebase features to deliver powerful insights. It enables you to view event logs in Crashlytics, notification effectiveness in FCM, deep link performance for Dynamic Links, and in-app purchase data from Google Play. It powers advanced audience targeting in Remote Config, Predictions, and more.

Google Analytics acts as a layer of intelligence in the Firebase console to provide you with more actionable insights about how to develop a high quality app, grow your user base, and earn more money.

To get started, read the documentation.

How do I segment users who have have not met some criterion?

You can reframe the problem by "negatively targeting" these users. For example, reframe the problem as "Don't show ads to people who have bought something", and form an audience of those users to target.

How do I control how my Analytics data is shared with rest of Firebase?

By default, your Google Analytics data is used to enhance other Firebase and Google features. You can control how your Google Analytics data is shared in your project settings anytime. Learn more about Data sharing settings.

What is the new fully upgraded Google Analytics account?

You can read more about the new Google Analytics upgrade in our blog post.

How do I know if I'm using Google Analytics for Firebase or a fully upgraded Google Analytics account?

What will happen to my data when I upgrade to the new Google Analytics for Firebase?

What is Firebase User Segmentation Storage?

Firebase User Segmentation Storage stores audience lists you've created to provide targeting information to other Firebase services that use them, such as Crashlytics, FCM, Predictions, and more.

Why don't I see any data after unlinking my app from Google Analytics?

Your analytics data resides within the Google Analytics property - not within the Firebase project. If you delete or unlink the property, then your data is unlinked from your project as well. The data still resides in that property, however, and you can always relink it to your project.
Creating a new Google Analytics account (and new property) will result in having a blank analytics dashboard in the Firebase console.

Why do I get an error when trying to upgrade my project to the new Google Analytics experience?

If you are experiencing and error when upgrading, such as:

  The operation has failed (Reason: Requested entity
  already exists)
  

or

  The operation has failed (Reason: Precondition check failed)
  

This means that there is an association between your project and an already existing Google Analytics property. You can unlink the property, delete it, or upgrade through the Google Analytics interface.

If this is still an issue, you can use the REST API to unlink by using the removeAnalytics method, and use the addGoogleAnalytics method to link a new property.

You can then move the data from one property to another, by following the steps described here.

Will audiences and/or events defined in Google Analytics be available on the Firebase dashboard?

Your audiences and user properties will be synced. For some features, you'll need to use the Google Analytics interface, such as segmentation and closed funnels. You can access the Google Analytics interface directly via deep-links from the Firebase console. Any changes you make from the Firebase Console can also be performed in Google Analytics, and those changes will be reflected in Firebase.

Firebase Authentication: Which countries are supported for phone authentication?

Firebase Authentication supports phone number verification across the the world, but not all networks reliably deliver our verification messages. The following countries have good rates of delivery, and should be expected to work well for phone number sign in.

Crash Reporting: Why are there fewer crash reports in Analytics than Crash Reporting?

Crash Reporting creates a separate background process to upload crash info. If your app extends the Android Application class, you must ensure it is multi-process safe. Otherwise, it may cause concurrency issues. When an app extends an Application object, this object gets instantiated for each process in a multi-process app. Consider the following when adding Crash Reporting to your app:

1. If the implementation of this object accesses any out-of-process state (a database, the file system, shared preferences, etc), or performs other actions not safe for a multi-process environment, concurrency issues might arise. This is because multiple instances of the Application object may run simultaneously.
2. Many third-party libraries keep out-of-process state (e.g. in a local database) and are subject to the same concurrency issues if they are initialized from the Application object. If your app fits this description and you plan to use Crash Reporting in your app, we strongly encourage you to consider moving the Application logic to Content Providers, or to Android Activities. Any Application logic that is not safe for a multi-process environment can have unintended effects on your app.

Crash Reporting automatically exports captured errors to Google Analytics as app_exception events. Currently on Android, you may see a significant discrepancy between the number of Crash Reporting errors and Analytics app_exception events.

Cloud Messaging: What's the difference between the Notifications composer and Cloud Messaging?

Firebase Cloud Messaging provides a complete set of messaging capabilities through its client SDKs and HTTP and XMPP server protocols. For deployments with more complex messaging requirements, FCM is the right choice.

The Notifications composer is a lightweight, serverless messaging solution built on Firebase Cloud Messaging. With a user-friendly graphical console and reduced coding requirements, the Notifications composer lets users easily send messages to reengage and retain users, foster app growth, and support marketing campaigns.

Hosting: Why does my Hosting release history table in the Firebase console show file counts that are more than what my local project actually has?

Firebase automatically adds extra files containing metadata about the Hosting site, and these files are included in the total file count for the release.

Cloud Messaging: Apple announced they're decprecating the legacy binary protocol for APNs. Do I need to do anything?

No. Firebase Cloud Messaging swtiched to the HTTP/2-based APNs protocol in 2017. If you are using FCM to send notifications to iOS devices, there should be no action required on your part.

Cloud Messaging: Do I need to use other Firebase services in order to use FCM?

You can use Firebase Cloud Messaging as a standalone component, in the same manner as you did with GCM, without using other Firebase services.

Cloud Messaging: I am an existing Google Cloud Messaging (GCM) developer. Should I move to Firebase Cloud Messaging?

FCM is the new version of GCM under the Firebase brand. It inherits GCM’s core infrastructure, with new SDKs to make Cloud Messaging development easier.

Benefits of upgrading to FCM SDK include:

• Simpler client development. You no longer have to write your own registration or subscription retry logic.
• An out-of-the-box notification solution. You can use the Notifications composer, a serverless notifications solution with a web console that lets anyone send notifications to target specific audiences based on insights from Google Analytics for Firebase.

To upgrade from GCM SDKs to FCM SDKs, see the guides for migrating Android and iOS apps.

Cloud Messaging: Why do my targeted devices apparently fail to receive messages?

When it looks like devices haven't successfully received messages, check first for these two potential causes:

Foreground message handling for notification messages. Client apps need to add message handling logic to handle notification messages when the app is in the foreground on the device. See the details for iOS and Android.

Network firewall restrictions. If your organization has a firewall that restricts the traffic to or from the Internet, you need to configure it to allow connectivity with FCM in order for your Firebase Cloud Messaging client apps to receive messages. The ports to open are:

• 5228
• 5229
• 5230

FCM usually uses 5228, but it sometimes uses 5229 and 5230. FCM does not provide specific IPs, so you should allow your firewall to accept outgoing connections to all IP addresses contained in the IP blocks listed in Google's ASN of 15169.

Cloud Messaging: I have implemented onMessageReceived in my Android app, but it is not being called.

When your app is in the background, notification messages are displayed in the system tray, and onMessageReceived is not called. For notification messages with a data payload, the notification message is displayed in the system tray, and the data that was included with the notification message can be retrieved from the intent launched when the user taps on the notification.

For more information, see Receive and handle messages.

Realtime Database: Why was my Realtime Database reported bandwidth lower than average between September 2016 and March 2017?

For our bandwidth calculations, we normally include SSL encryption overhead (based on layer 5 of the OSI model). However, in September 2016, we introduced a bug that caused our bandwidth reporting to ignore encryption overhead. This might have resulted in artificially low reported bandwidth and bills on your account for a few months.

We released a fix for the bug in late March 2017, returning bandwidth reporting and billing to their normal levels.

Realtime Database: What are the scaling limitations of the Realtime Database?

Each Realtime Database instance has limits on the number of write operations per second. For small writes, this limit is approximately 1000 write operations per second. If you are approaching this limit, batching operations using multi-path updates can help you achieve higher throughput.

In addition, each database instance has a cap on the number of simultaneous database connections. Our default limits are large enough for most applications. If you are building an app that requires additional scale, you may need to shard your application across multiple database instances for added scale. You may also consider Cloud Firestore as an alternative database.

Realtime Database: What can I do if I'm over my Realtime Database usage limits?

If you've received an email alert or notification in the Firebase console that you've exceeded your Realtime Database usage limits, you can address it based on the usage limit you've exceeded. To see your Realtime Database usage, go to the Realtime Database usage section of the Firebase console.

If you're over your download limit, you can upgrade your Firebase plan or wait until your download limit resets at the start of your next billing cycle. To decrease your downloads, try the following steps:

• Add queries to limit the data that your listen operations return.
• Check for unindexed queries.
• Use listeners that only download updates to data — for example, on() instead of once().
• Use security rules to block unauthorized downloads.

If you're over your storage limit, upgrade your plan to avoid service disruptions. To reduce the amount of data in your database, try the following steps:

• Run periodic cleanup jobs.
• Reduce any duplicate data in your database.

Note that it may take some time to see any data deletions reflected in your storage allotment.

If you're over your simultaneous database connections limit, upgrade your plan to avoid any service disruptions. To manage simultaneous connections to your database, try connecting via users via the REST API if they don't require a realtime connection.

Storage: Why can't I use Cloud Storage?

Firebase Storage creates a default bucket in the Google App Engine free tier. This allows you to quickly get up and running with Firebase and Firebase Storage, without having to put in a credit card or enable a billing account. It also allows you to easily share data between Firebase and a Google Cloud Platform project.

There are, however, two known cases where this bucket cannot be created and you will be unable to use Firebase Storage:

• A project imported from Google Cloud Platform which had a Google App Engine Master/Slave Datastore application.
• A project imported from Google Cloud Platform which has domain prefixed projects. For example: domain.com:project-1234.

There are currently no workarounds to these issues, and we recommend that you create a new project in the Firebase console and enable Firebase Storage in that project.

Remote Config: Why don't fetched values change the behavior and appearance of my app?

Unless you fetch values with fetchAndActivate(), values are stored locally but not activated. To activate fetched values so that they can take effect, call activate. This design lets you control when the behavior and appearance of your app changes, because you can choose when to call activate. After you call activate, your app source code determines when updated parameter values are used.

For example, you could fetch values and then activate them the next time a user starts your app, which removes the need to delay app startup while your app waits for fetched values from the service. Changes to your app's behavior and appearance then occur when your app uses the updated parameter values.

To learn more about the Remote Config API and usage model, see Remote Config API Overview .

Remote Config: I am making a lot of fetch requests while developing my app. Why doesn't my app always get the latest values from the service when it sends fetch requests?

During app development, you might want to fetch and activate configs very frequently (many times per hour) to let you rapidly iterate as you develop and test your app. To accommodate rapid iteration on a project with up to 10 developers, you can temporarily set a FirebaseRemoteConfigSettings object with a low minimum fetch interval (setMinimumFetchIntervalInSeconds) in your app.

Remote Config: How quickly does the Remote Config service return fetched values after my app sends a fetch request?

Devices usually receive fetched values in less than a second, and often receive fetched values in milliseconds. The Remote Config service handles fetch requests within milliseconds, but the time required to complete a fetch request will depend on the network speed of the device and the latency of the network connection used by the device.

If your goal is to make fetched values take effect in your app as soon as possible, but without creating a jarring user experience, consider adding calls to fetchAndActivate each time that your app does a full screen refresh.

Dynamic Links: Why does my Android app access each Dynamic Link twice?

The getInvitation API clears the saved Dynamic Link to prevent it from being accessed twice. Be sure to call this API with the autoLaunchDeepLink parameter set to false in each of the deep link activities to clear it for the case when the activity is triggered outside the main activity.

Notifications composer: What's the difference between the Notifications composer and Cloud Messaging?

The Notifications composer is a lightweight, serverless messaging solution built on Firebase Cloud Messaging. With a user-friendly graphical console and reduced coding requirements, the Notifications composer lets users easily send messages to reengage and retain users, foster app growth, and support marketing campaigns.

Firebase Cloud Messaging provides a complete set of messaging capabilities through its client SDKs and HTTP and XMPP server protocols. For deployments with more complex messaging requirements, FCM is the right choice.

Here's a comparison of the messaging capabilities provided by Firebase Cloud Messaging and the Notifications composer:

Notifications composer: I am an existing Google Cloud Messaging (GCM) developer, and I want to use the Notifications composer. What should I do?

The Notifications composer is an out-of-the-box solution that lets anyone send notifications to target specific audiences based on insights from Google Analytics for Firebase. Also, the Notifications composer provides funnel analysis for every message, allowing easy evaluation of notification effectiveness.

If you are an existing GCM developer, to use the Notifications composer you have to upgrade from GCM SDKs to FCM SDKs. See the guides for migrating Android and iOS apps.

Predictions: I just added Google Analytics to my app. When should I expect to see predictions in the console?

Predictions are based on your users’ behavior, and the more history that's available, the better. At a bare minimum, Firebase Predictions needs two weeks of data: one week of activity to train on, and then one week to see what that activity led to (churning, spending, etc.). Beyond the first two weeks, the quality of the predictions will typically increase as Predictions observes longer sequences of user activity.

Predictions: How long does it take for predictions to be made about a new user?

For an app that is already instrumented with Google Analytics and trained with baseline data, predictions can be made for new users as early as the next day after they start using the app.

App Indexing: Can Google Search index multiple languages for a single app?

Google Search supports the following multi-language cases:

• The associated website has unique URLs for each language, and there is one corresponding app HTTP URL for each web URL.
• The associated website has unique URLs for each language, but there is only one app HTTP URL. The app uses system language settings to display the correct language content.
• The associated website has one URL for all languages (or it supports only one language), and there is one corresponding app URL. The website and the application must display the content in the same language when the user has set no preference.

App Indexing: Can App Indexing support multiple websites for an app?

Yes. Make sure that each associated website is verified for the Android app via Google Play Console. Learn how to verify your app.

App Indexing: Do sitemaps need to be added via the Search Console?

iOS does not require sitemaps, and Android does not require them as long as your app supports HTTP URLs. For custom URLs, you do not need to add sitemaps via Search Console. You can reference sitemaps in your robots.txt file and Google Search will use them. Learn more about Managing sitemaps. However, submitting a sitemap through Search Console lets you see statistics on submitted and indexed HTTP URLs in Search Console.

AdMob: Will I be able to link my Windows apps to Firebase?

Windows apps are not currently supported in the Firebase console.

AdMob: Why can't I link my AdMob account from the Firebase console?

You can link an AdMob app to a Firebase app via the AdMob console. In order to link the account you need to be both a Firebase project owner and an AdMob admin.

AdMob: Can multiple users link their AdMob account to a Firebase app?

No, every AdMob account will only have one primary user. The primary user is the first user to accept the Firebase terms of service.

A/B Testing: How many experiments can I create and run?

You are allowed up to 100 experiments per project, which could consist of up to 24 running experiments, with the rest as draft or completed.