Do you need to create mobile and web applications for your business? Well, you can try flutter. It is one of the remarkable open-source frameworks for developing the cross-platform app. Hiring the best flutter app development company like Flutter Agency is good to create a multiplatform app for your business. They develop mobile and web applications from a single codebase. 

Explained Firebase 

Now, many flutter app developers are deploying their apps to firebase hosting. Firebase is the famous Google-backed app development software with numerous tools. It offers tools like tracking systematic, reporting, designing marketing, and eliminating app errors. 

A developer using firebase hosting for their flutter app development can get a better outcome.  An individual can create a web application without any hassle using a single command. 

It serves dynamic and static content to a worldwide content delivery network. Likewise, they can merge the firebase hosting with the cloud run for developing and hosting microservices on the platform. 

Setting up emulator for VSCode is one of the prime requirements for Flutter development, developing a flutter app and deploying it to firebase hosting does not work properly with flutter run. Special URLs do not appear when you use flutter run. Using the Firebase server, you cannot use the hot reload feature.

Under my app/web/ directory, I have the following local files:


# containing firebase.initializeApp(myFirebaseConfig);


# manually downloaded from the gstaticcdn


  # ... (etc)

However, the firebase deploys the _ directory, which is not good. Having to set it in each local app development background manually is irritating. Firebase Login, Firebase Init, Flutter Serve, and access to the /_/ directory should work without issues.

In this post, you will learn how to use firebase reserved hosted URL for flutter app development.

Open the firebase SKD file from the reserved URL

On the website, the firebase hosting reserved URL starts with /_ _, which makes it simple to utilize at once the firebase items with the firebase hosting. Besides, use the reserved URL while running the application on the local server or set it up to firebase.  

Adding scripts to reserved URLs

If the developer installs the firebase hosting over HTTP/2, the app's performance can be increased by loading the file from a similar source. It also serves a variety of Firebase JavaScript SDK versions from a specific URL, such as the one below. 


It is advised to load the library, which you have already used in the application. You can add the following scripts to the bottom of your <body> tag before using any firebase services to use only Authentication and Cloud Firestore:


 <!-- Insert these scripts at the bottom of the HTML, but before you use any Firebase services --> 

<!-- Firebase App (the core Firebase SDK) is always required and must be listed first -->


 <!-- Add Firebase products that you want to use -->




Automatic SDK configuration

SDK auto-configuration allows you to manage several environments without hassle like dev, production, staging, and others from one codebase. In addition, the developer can install similar code to various firebase app development projects by depending on the reserved firebase hosting URLs.

Reserved namespace offers many configurations to start the SDK for firebase applications linked with the hosting website to host SDK automatically. Besides, the script offers the initialization of SDK and Firebase configuration so one can include it straightforwardly. 

<!-- Load the Firebase SDKs before loading this file -->


Test the dynamic Firebase application development project locally or deploy it to Firebase hosting. The below-given script configures the Firebase JavaScript SDK and initializes it automatically.

Do you wish to control the initialization? Then, there is a firebase configuration principles in the form of JSON. So, you can try it for better outcomes!

fetch('/__/firebase/init.json').then(async response => {

firebase.initializeApp(await response.json());


Authentication assistant 

As a result of the reserved namespace, the firebase authentication supports the special HTML and JavaScript for completing OAuth authentication. Thus, every firebase plan has a special firebase subdomain that boosts the firebase authentication security. 

The developer can set their custom domain for authDomain when using firebase.initializeApp(). Developers can specify a customized domain when initializing Firebase SDKs, identifying that domain.

Reserved URLs and service workers

If the URL doesn't match the precached substances list, the expert may build the service workers, which have navigation fallback, and render the specific URL by default if it doesn't match the precached substance list.  

To exclude the reserved namespace from the navigation fallback options, individuals can use the sw-precache library:


navigateFallbackWhitelist: [/^(?!\/__).*/]


Developers should not intercept double-underscore requests in the service worker, as this is reserved for firebase usage.

Firebase Hosting: How it works

Firebase Hosting is specially created for app developers. Applications and websites are more popular than constantly increasing the front-end JavaScript frameworks such as stable generator tools. 

It does not matter if the web developer is setting up a complex PWA or a simple web application landing page. Firebase hosting offers amazing features, tools, and infrastructure to manage apps and sites effortlessly. 

It is easy to install files from the desktop’s local director and the firebase hosting server with the help of firebase CLI. In addition, they can utilize the cloud function for cloud run to work dynamic content on the website elsewhere, serving stable content. The closest CDN edge servers serve all content via SSL connections.

It is important to examine the changes before the final step. The developers use the firebase local emulator suite to track backend resources and applications at the URL hosted locally. Firebase Hosting has simple hosting configuration methods that enable the developer to create a sophisticated progressive web application. Also, it lets them rewrite URLs easily for the local content, client-side routing, and others. All your documents are served safely because firebase supplies SSL certificates automatically.


If you have any doubt about using firebase reserved hosted URL, you can hire Flutter developers from Flutter Agency. The developer will guide you to complete the app development project smoothly and effectively.