How to configure ads.txt and sellers.json for better ad revenue

Digital ad fraud costs advertisers billions annually, and publishers can lose revenue due to unauthorised reselling of their inventory. Implementing ads.txt and sellers.json correctly ensures that advertisers buy directly from authorised sources, increasing trust and improving demand for your ad space. By maintaining transparency, publishers can attract higher-quality advertisers, reduce fraudulent activity, and secure better rates for their inventory.

Proper configuration helps:

• Prevent domain spoofing – Ensures only authorised resellers can sell your ad inventory, reducing ad fraud.
• Improve advertiser trust – Brands prefer sites that comply with industry transparency standards.
• Maximise ad revenue – Legitimate demand increases when your inventory is verified, leading to higher CPMs.
• Comply with industry standards – Many DSPs (Demand-Side Platforms) require ads.txt and sellers.json for bidding eligibility.
• Enhance brand reputation – A properly structured ads.txt file demonstrates credibility and legitimacy in the programmatic ecosystem.

Step 1: Configure ads.txt

What is ads.txt?

Ads.txt (Authorized Digital Sellers) is an IAB Tech Lab initiative that allows publishers to declare who is authorised to sell their digital ad inventory. This prevents unauthorised sellers from misrepresenting themselves and improves transparency in programmatic advertising.

How to set up ads.txt:

1. Access your website’s root directory – The file must be placed at yourdomain.com/ads.txt for it to be valid.
2. Create or edit your ads.txt file – If one does not exist, create a plain text file.
3. List authorised ad sellers – Format each entry as follows:

   adnetwork.com, publisherID, DIRECT/RESELLER, certificationID
   

4. Obtain details from your ad partners – Platforms like Google AdSense, Google Ad Manager, AdX, and SSPs provide the necessary details.
5. Verify correct implementation – Use Google’s ads.txt validator or third-party tools to check for errors.

Example ads.txt file:

google.com, pub-1234567890, DIRECT, f08c47fec0942fa0
appnexus.com, 98765, RESELLER, f08c47fec0942fa0
rubiconproject.com, 54321, DIRECT, 123abc456def789ghi

• DIRECT means the publisher has a direct contract with the ad exchange.
• RESELLER indicates that the seller is authorised to resell the inventory on behalf of the publisher.
• Certification ID is an optional identifier assigned to ad networks by the IAB for verification.

Step 2: Configure sellers.json

What is sellers.json?

Sellers.json is another IAB Tech Lab standard that allows buyers to verify the identity of publishers and resellers in programmatic advertising. This ensures that advertisers can see where their money is going and avoid fraudulent transactions.

How to configure sellers.json:

1. Check your SSPs and ad platforms – Most major platforms (Google Ad Manager, OpenX, Magnite, Index Exchange) automatically list you in their sellers.json file.
2. Ensure transparency settings are correct – Some platforms allow you to choose between CONFIDENTIAL and TRANSPARENT seller status.
3. Use TRANSPARENT status for higher trust – Publicly displaying your publisher details helps advertisers verify authenticity, leading to better demand.
4. Verify your entry – Platforms like Google provide a sellers.json lookup tool to check if you are correctly listed.
5. Manually review resellers – Avoid unnecessary intermediaries that could dilute your ad revenue.

Example sellers.json entry:

{
  "seller_id": "pub-1234567890",
  "is_confidential": 0,
  "seller_type": "PUBLISHER",
  "name": "Example News Site"
}

• is_confidential: 0 means the publisher is fully visible to buyers, increasing transparency.
• seller_type: PUBLISHER indicates that you own the inventory and are not just a reseller.
• If is_confidential: 1, your details remain hidden, but this can reduce advertiser trust and limit demand.

Step 3: Monitor and update regularly

Ads.txt and sellers.json require ongoing maintenance to ensure compliance and revenue optimisation. Incorrect or outdated entries can cause missed revenue opportunities or limit demand from premium advertisers.

Best practices for managing ads.txt and sellers.json:

• Review regularly – Keep your ads.txt file updated when adding or removing ad partners.
• Avoid excessive resellers – Too many intermediaries reduce transparency and lower CPMs.
• Monitor ads.txt errors – Use Google Ad Manager reports to detect invalid or incorrectly formatted entries.
• Check for unauthorised sellers – Review reports from demand partners to ensure no unauthorised sources are selling your inventory.
• Ensure demand partners support sellers.json – Some ad networks might not provide full transparency, affecting your credibility.
• Audit your ad revenue impact – Compare performance before and after changes to ads.txt and sellers.json to measure improvements.
• Communicate with partners – Request ad partners to confirm they are correctly listed in sellers.json and provide necessary details.

Step 4: Troubleshoot common issues

Common ads.txt mistakes and fixes:

• Incorrect file placement – Ensure ads.txt is placed in the root domain (e.g., example.com/ads.txt).
• Misspelled ad network domains – Double-check entries against official ad partner documentation.
• Using the wrong seller type – Ensure RESELLER is used only when appropriate.
• Too many resellers – Limit indirect sellers to increase direct demand.

Common sellers.json issues:

• Not appearing in SSP’s sellers.json – Contact your SSP to ensure you are listed.
• Incorrect confidentiality settings – Change from CONFIDENTIAL to TRANSPARENT to build advertiser trust.
• Conflicting seller IDs – Verify that your seller ID matches across platforms.

Final thoughts

Configuring ads.txt and sellers.json correctly helps publishers prevent ad fraud, maintain trust with advertisers, and optimise revenue. By keeping these files up to date, ensuring transparency, and reducing unauthorised reselling, you create a safer and more profitable programmatic advertising environment. Regular audits, compliance checks, and communication with demand partners will help maintain a healthy and efficient ad revenue stream.