app-ads.txt

Like ads.txt, app-ads.txt is a text file that app developers upload to their developer website listed on Google Play and the App Store. It lists the ad sources authorized to sell that developer’s in-app inventory. Just like on the web, the IAB created this standard to let buyers know who is and isn’t authorized to buy and sell specific in-app inventory. It is a key step that protects app developers from unauthorized reselling or inventory fraud.

Publishers who adopt app-ads.txt are likely to earn more revenue, as many brand buyers and advertisers require publishers to have a valid app-ads.txt file and will not buy inventory on apps without one. 

How app-ads.txt Works and Benefits Mobile Apps

A demand-side platform (DSP) looking to bid on app inventory scans the app-ads.txt file on a developer’s website to verify which ad sources are authorized to sell that app’s inventory. The DSP will only accept bid requests from ad sources listed on the file and authorized by the app developer.

How app-ads.txt can benefit your mobile apps:

• Access to premium brand demand: Having a valid and properly formatted app-ads.txt file makes your app inventory eligible for campaigns from premium advertisers and brand buyers who rely on the standard to verify trusted supply sources.
• Fraud reduction: By publicly listing only the partners you authorize, app-ads.txt helps block unauthorized sellers and spoofed inventory, ensuring that revenue from your apps goes directly to you.

Implement app-ads.txt

Step 1. Add Your Developer Website to the App Stores

Add your developer website domain to your app listings on Google Play and the App Store. Use one canonical root domain (for example, yourstudio.com) across all apps. Buyers and monetization partners use this URL to discover and verify your app-ads.txt file.

Step 2. Create Your app-ads.txt File

Create a plain-text file named app-ads.txt (UTF-8) in the root directory of your developer website. In this file, list all authorized partners using the exact format they provide. Each ad network you work with can share the specific lines you need to include:

partner-domain.com, <YOUR_ACCOUNT_ID>, DIRECT|RESELLER, <CERT_ID (optional)>

Place your OWNERDOMAIN line at the top of the file so that your app-ads.txt, store listings, and business domain all align under one identity. This helps buyers connect your file to Sellers.json and verify ownership clearly:

OWNERDOMAIN=yourstudio.com

For example (this is illustrative only; use your partners’ exact lines):

OWNERDOMAIN=yourstudio.com

vungle.com, <YOUR_VUNGLE_PUBLISHER_ACCOUNT_ID>, DIRECT, c107d686becd2d77
google.com, pub-<YOUR_ADMOB_PUBLISHER_ID>, DIRECT, f08c47fec0942fa0
example-ssp.com, <YOUR_ID>, RESELLER, <CERT_ID>

Make sure your file uses UTF-8 character encoding and that your web server serves it as Content-Type: text/plain. Every authorized seller should appear exactly as listed by each ad network or exchange.

For full field definitions and formatting requirements, review the IAB Tech Lab’s Authorized Sellers for Apps specification.

Step 3. Add Liftoff to Your app-ads.txt File

Add Liftoff to your app-ads.txt file by updating your Seller ID and including the most up-to-date Liftoff Monetize entries. You can download liftoff app-ads.txt here: https://publisher.vungle.com/vungleAdsTxt

Replace <YOUR_VUNGLE_PUBLISHER_ACCOUNT_ID> with your actual Publisher Account ID (Seller ID). You can find this in the top right corner of your Liftoff Monetize Dashboard, as shown: 

Entering this incorrectly or omitting it can prevent buyers from validating your inventory and may lead to lost revenue.

vungle.com, 53c9a946adeed4cbd2w5555a, DIRECT, c107d686becd2d77

After adding your Seller ID line, include the latest Liftoff Monetize list of authorized entries and paste the text block in your TXT file. Keeping this list current ensures your app remains eligible for Liftoff’s premium brand demand and maximizes access to advertiser budgets. Liftoff sends monthly email updates with any missing or new entries.

Download this file for our latest entries: Liftoff Monetize App-Ads.txt.

Step 4. Link Your Developer Website in the Liftoff Dashboard

In your Liftoff Monetize Dashboard, set the Developer website to the same root domain you listed in the app stores (for example, yourstudio.com).

Note: The IAB Sellers.json specification allows only one domain per Seller ID (Liftoff account). A Seller ID cannot validly represent more than one entity.

Step 5. Publish the app-ads.txt File

Host the file at the root of your domain so that it’s reachable at: https://yourstudio.com/app-ads.txt.
Serve it with HTTP header `` (UTF-8). If your file is hosted on a different root domain, keep it to one cross-domain redirect; internal redirects on the same root are fine.

Quick checks:

https://yourstudio.com/app-ads.txt     # should show plain text
curl -I https://yourstudio.com/app-ads.txt   # look for Content-Type: text/plain

Re-validate whenever you add or remove partners, change domains, or move hosting to ensure buyers always see the latest authorization list.

Best Practices for app-ads.txt

• Keep your app-ads.txt current: Update your file whenever you add, remove, or change partners. Regular updates ensure buyers always recognize your authorized sellers.
• Validate after publishing: Run validation tools or cURL checks to confirm your app-ads.txt file is reachable and formatted correctly. Validation helps prevent missed bids from technical issues.
• Follow the IAB spec: Review the latest IAB Authorized Sellers for Apps and Sellers.json specifications to stay aligned with industry standards.