Adstxt

Why OWNERDOMAIN and MANAGERDOMAIN Fields Are Essential in Ads.txt

Transfon

Transfon

4 min read

Since its launch in 2017, Ads.txt (Authorized Digital Sellers) has been a game-changer in fighting ad fraud and bringing transparency to programmatic advertising. It’s basically a way for publishers to publicly declare which companies are authorized to sell their ad inventory—helping advertisers avoid shady resellers and unauthorized middlemen.

But as ad tech has evolved, things have gotten more complicated. Many publishers now rely on third-party ad managers, and advertisers struggle to tell the difference between inventory sold directly by a publisher and inventory managed by someone else. That’s where the Ads.txt 1.1 update comes in, introducing two key fields: OWNERDOMAIN and MANAGERDOMAIN.

These fields add much-needed clarity by making it easier to see who actually owns a website and who’s managing its ad inventory. If you’re in the ad ops world, understanding and implementing these fields is crucial. Let’s break it down.

What Are OWNERDOMAIN and MANAGERDOMAIN?

Both fields serve distinct purposes in identifying the key players behind an ad inventory source.

OWNERDOMAIN: Who Owns the Site?

The OWNERDOMAIN field tells you who the actual parent company of a website is. This is particularly useful for advertisers who want to make sure they’re buying directly from the real owner—not some random reseller pretending to be legit.

Example:

OWNERDOMAIN=mywebsite.com

If a publisher owns multiple domains, all of them would point to the same OWNERDOMAIN.

MANAGERDOMAIN: Who’s Managing the Ads?

The MANAGERDOMAIN field clarifies which third-party company is responsible for managing a publisher’s ad inventory. This is especially helpful when a site works with different ad managers across regions.

Example:

MANAGERDOMAIN=agency.com

Or, if different managers handle different markets:

MANAGERDOMAIN=agency-us.com, UK
MANAGERDOMAIN=agency-uk.com, US

Why Do These Fields Matter?

The more complex programmatic advertising gets, the harder it is to verify whether an ad is being sold by an authorized seller. Without OWNERDOMAIN and MANAGERDOMAIN, advertisers can’t easily tell if they’re buying inventory from a direct source or through an intermediary. Here’s why that’s a problem:

  1. Advertisers Want Direct Deals – Many brands prefer to buy directly from publishers to avoid unnecessary middlemen. OWNERDOMAIN makes it clear who actually owns the site.
  2. Small Publishers Rely on Ad Managers – Many publishers don’t sell their own inventory. Instead, they work with ad management platforms. MANAGERDOMAIN helps advertisers identify these relationships.
  3. Existing Tools Weren’t Enough – While Sellers.json and the SupplyChain object (SChain) offer some transparency, they don’t clearly differentiate between ad managers and resellers. MANAGERDOMAIN fills that gap.

By tying Ads.txt 1.1 together with Sellers.json and SChain, the industry gets a more complete picture of the ad supply chain—making fraud and misrepresentation much harder.

How OWNERDOMAIN and MANAGERDOMAIN Build Trust

For advertisers, OWNERDOMAIN and MANAGERDOMAIN provide a much-needed trust signal. Here’s how:

  • OWNERDOMAIN stops domain spoofing – It ensures the seller is actually who they claim to be.
  • MANAGERDOMAIN clarifies ad management relationships – If a publisher uses an ad management service, advertisers can verify that it’s a legitimate partnership.
  • More transparency = better bidding decisions – Demand-side platforms (DSPs) can optimize campaigns by prioritizing verified, high-quality inventory.

How to Implement OWNERDOMAIN and MANAGERDOMAIN

1. Update Your Ads.txt File

Publishers should assess their setup:

  • If they manage their own inventory, they only need to add OWNERDOMAIN.
  • If they use a third-party ad manager, they should include both OWNERDOMAIN and MANAGERDOMAIN.

Example for a website owned by Amprev.com:

OWNERDOMAIN=mywebsite.com
MANAGERDOMAIN=amprev.com

2. Keep Information Accurate

  • OWNERDOMAIN should match the seller.domain field in Sellers.json.
  • If different ad managers operate in different countries, list them separately:
MANAGERDOMAIN=amprev.com, UK
MANAGERDOMAIN=amprev.com, US
  • Regularly update your Ads.txt file in Ads.txt Manager to reflect any changes.

3. Avoid These Common Mistakes

  • Ensure OWNERDOMAIN matches Sellers.json.
  • Only list one OWNERDOMAIN per Ads.txt file.
  • Only include MANAGERDOMAIN entries for companies directly managing a publisher’s inventory.

Final Thoughts

The introduction of OWNERDOMAIN and MANAGERDOMAIN in Ads.txt 1.1 isn’t just a minor tweak—it’s a significant improvement for transparency in programmatic advertising. These fields help advertisers make better buying decisions, prevent fraud, and ensure that ad dollars go where they’re supposed to.

For publishers, properly implementing these fields means staying attractive to advertisers, reducing unauthorized resale, and maintaining trust in their inventory. As Ads.txt 1.1 adoption grows, these fields aren’t optional—they’re essential for any publisher serious about ad revenue and long-term sustainability.

Adstxt.dev is the best Ads.txt Manager for publishers and ad networks.