Authorized Sellers for Apps (app-ads.txt)

Authorized Sellers for Apps, also known as app-ads.txt, is an IAB initiative that helps protect your app ad inventory from ad fraud. You create app-ads.txt files to identify who is authorized to sell your inventory. Identifying authorized sellers can help you receive advertiser spend that might have otherwise gone toward counterfeit inventory of spoofed apps.

The app-ads.txt files are publicly available and crawlable by exchanges, supply-side platforms (SSP), other buyers, and third-party vendors.

Use of app-ads.txt is not mandatory, but is highly recommended, especially if you are concerned that others may be spoofing your app.

An app-ads.txt file is a text file that an app developer posts in the root domain of their app's developer website. It contains a list of entities authorized to sell that publisher's inventory. The usage of the app-ads.txt file requires that publishers have a web domain to publish their authorized sellers list for different ad tech vendors to crawl. There are a number of domain hosting solutions that allow for the arbitrary hosting of files including Firebase.

Prerequisites

Read Set up an app-ads.txt file for your app.
Browse through Manage your Firebase projects.

How to set up app-ads.txt for your apps

If you haven't already, create a text file and save it with the name "app-ads.txt".
Copy and paste the following code snippet into your app-ads.txt file. (Replace pub-00000000000000 with your publisher ID. Your publisher ID can be found at AdMob console > Settings.)
```
google.com, pub-00000000000000, DIRECT, f08c47fec0942fa0
```
Publish your app-ads.txt at the root of your developer website (for example, https://example.com/app-ads.txt). Make sure the domain is entered exactly as listed on Google Play.

Note: If your website does not allow you to publish app-ads.txt on the root level, you can use Firebase Hosting as one of the options for hosting your app-ads.txt file.
Wait at least 24 hours for AdMob to crawl and verify your app-ads.txt file.
Come back to AdMob and check your app-ads.txt status.

Publish app-ads.txt with Firebase Hosting

If you have a website that disallows the uploading of your app-ads.txt file at the root level (e.g., a site built and hosted by a site-generation service), you can use Firebase Hosting to host your app-ads.txt file.

Firebase offers a free, fast, and reliable way to host your app-ads.txt file with your own custom domain or on Firebase project's free subdomains: web.app and firebaseapp.com.

Before you begin

You'll need to have a Firebase project to publish app-ads.txt with Firebase Hosting. If you don't have a Firebase project, create a new one by following the developer guide.

If you've already linked your AdMob apps to Firebase or your app is using one of the Firebase products (e.g., Google Analytics for Firebase, Remote Config, etc.), you can use the existing Firebase project.

Install the Firebase CLI

You can install the Firebase CLI by using npm (Node Package Manager). However, if you're not familiar with Node.js, you can use the standalone binary instead.

Visit the Firebase CLI documentation to learn how to install the CLI or update to its latest version.

Initialize your project

To initialize your Firebase project in your local machine, run the following command from the root of your project directory.

firebase init

During project initialization, from the Firebase CLI prompts:

Select to set up Hosting.
Select a Firebase project to connect to your local project directory.

Select Use an existing project, then choose a project from the list that you want to connect.
Specify a directory to use as your public root directory.

Press enter to select a default one (public).
Choose a configuration for your site.

Since the website you're going to create is not a single-page app, select N.

At the end of initialization, Firebase creates and adds two files to the root of your local project directory:

A public directory that contains files hosted on your website.
A firebase.json configuration file that lists your project configuration.
A .firebaserc file that stores your project alias.

Publish app-ads.txt

To publish app-ads.txt to your site:

Put the app-ads.txt file into the public directory in your local project directory.
Run the following command from the root of your local project directory:
```
firebase deploy --only hosting
```
Once deployment is complete, visit the following URL to make sure app-ads.txt is published. (PROJECT_ID is your Firebase project ID.)

https://PROJECT_ID.web.app/app-ads.txt

Example: If "awesome-project" is the project ID, enter https://awesome-project.web.app/app-ads.txt in the address bar of your browser.

Add domain/subdomain to your app's store listing

In order for your app-ads.txt file to be crawled, you will need to list the newly created domain or subdomain in your app listing on Google Play.

Update the developer website in the app store listing as follows:

https://PROJECT_ID.web.app

Configure redirection settings (optional)

If you have an existing website and plan to use Firebase Hosting just for hosting your app-ads.txt file, you can configure Firebase Hosting to redirect the landing page to your existing website.

Firebase Hosting will use public/index.html as a landing page by default when a user visits your site. To redirect users to the website that you want (for example, your app's social media page):

Open firebase.json file located in the root of your local project directory.

Under hosting object, add redirects object as follows:

"hosting": {
  ...
  "redirects": [
    {
      "source": "/",
      "destination": "URL_TO_REDIRECT",
      "type": 301
    }
  ]
}

For example, if the landing page URL is https://www.example.com, the redirect configuration will be as follows:

"hosting": {
  ...
  "redirects": [
    {
      "source": "/",
      "destination": "https://www.example.com",
      "type": 301
    }
  ]
}

Run the following command to deploy the changes to your site.
```
firebase deploy --only hosting
```
Once the deployment is complete, access your site (https://PROJECT_ID.web.app) to check whether the redirection setting is correct or not.