Ads.txt: Publishers’ Key to Combating Ad Fraud

Ads.txt: The Secret Weapon of Publishers Against Online Advertising Fraud

In the constantly evolving digital advertising ecosystem, ads.txt has become an essential tool for publishers concerned about protecting their revenue. This innovation introduced in 2017 by the IAB Tech Lab revolutionizes transparency and security in programmatic transactions.

What is ads.txt and why is it essential?

Ads.txt (Authorized Digital Sellers) is a simple text file that publishers place at the root of their domain. This mechanism allows them to publicly indicate which entities are authorized to sell their advertising inventory.

Indeed, its operation is based on a simple but powerful principle: transparency.

Imagine your website as a house. Without ads.txt, anyone could claim to sell advertising space on your behalf. With ads.txt, you clearly display the list of “authorized sellers” on your front door.

“Ads.txt is to publishers what SSL certificates are to website security: an essential standard for establishing trust in the digital ecosystem.” – Jerome HENRY – AI & Marketing Consultant

There are multiple benefits for publishers:

Protection against fraud: prevents “domain spoofing” and unauthorized sales
Increased revenue: verified inventories command higher prices
Enhanced trust: reassures buyers about the authenticity of the inventory
Strengthened control: precise management of business partners

Yet, despite these obvious benefits, some publishers still delay implementing it correctly. On one hand, they underestimate the financial losses related to fraud. On the other hand, they mistakenly consider the implementation to be complex.

How does ads.txt work in practice?

The ads.txt file follows a structured syntax that clearly identifies the relationships between publishers and sellers. Each line of the file contains four main elements, separated by commas:

domain.com, account_id, RELATIONSHIP_TYPE, certification_authority_id

Let’s analyze these elements:

domain.com: the domain of the authorized advertising partner
account_id: the unique account identifier with this partner
RELATIONSHIP_TYPE: DIRECT (direct relationship) or RESELLER (reseller)
certification_authority_id: optional parameter for authority identifiers

For example, a typical line might look like:

google.com, pub-1234567890, DIRECT, f08c47fec0942fa0

This line means that the Google AdSense account with ID pub-1234567890 is authorized to sell the publisher’s inventory directly.

Artificial Intelligence: Revolutionizing Ads.txt Implementation and Management

Artificial Intelligence is transforming how publishers implement and maintain their ads.txt files, making the process more efficient and effective. AI-powered tools now scan and analyze ads.txt files across millions of domains to identify patterns, discrepancies, and potential vulnerabilities. These systems can automatically detect unauthorized sellers, identify outdated entries, and recommend optimizations based on industry benchmarks. Advanced AI algorithms can also predict potential fraud attempts by monitoring unusual changes in the programmatic ecosystem and alerting publishers to suspicious activities. For large publishers managing multiple domains, AI tools can synchronize ads.txt files across properties while tailoring them to specific regional requirements. As one industry expert noted, “AI doesn’t just help manage ads.txt compliance—it transforms it from a static text file into a dynamic fraud prevention system that adapts to emerging threats in real-time.”

Innovations in ads.txt 1.1

Version 1.1 of ads.txt introduced essential concepts that further improve transparency:

OWNERDOMAIN: clearly identifies the domain owner
MANAGERDOMAIN: designates an exclusive partner for monetization
Geographic support: allows specifying managers by region

Consequently, these additions allow a better representation of complex business relationships in the programmatic ecosystem.

Here’s a more elaborate example of a modern ads.txt file:

# ads.txt for example.com
OWNERDOMAIN=publishergroup.com
MANAGERDOMAIN=admanager.com
google.com, pub-1234567890, DIRECT, f08c47fec0942fa0
adexchange.com, 123456, RESELLER
admanager.com, 789012, DIRECT
spotx.tv, 12345, RESELLER, 7842df1d2fe2db34

This file indicates that publishergroup.com is the domain owner, with admanager.com as the main manager for monetization.

Screen illustrating cybersecurity protection

The different use cases for ads.txt

Ads.txt adapts to various business configurations. Let’s examine the main implementation scenarios:

Internal monetization by the publisher

In this case, the publisher manages their relationships with exchange platforms themselves. Thus, the path is direct:

Publisher → Exchange → DSP

The corresponding ads.txt file would be:

OWNERDOMAIN=publisher.com
exchange.com, 1234, DIRECT

Monetization delegated to a partner

When a publisher entrusts their monetization to an exclusive partner, the journey becomes:

Publisher → Manager → Exchange → DSP

OWNERDOMAIN=publisher.com
MANAGERDOMAIN=manager.com
manager.com, 5678, DIRECT
exchange.com, 1235, RESELLER

Region-specific monetization

International publishers can designate different partners according to geographic areas:

OWNERDOMAIN=publisher.com
MANAGERDOMAIN=saleshouseDE.com, DE
saleshouseDE.com, 9876, DIRECT
exchange.com, 1236, RESELLER

Finally, this configuration indicates that saleshouseDE.com is the exclusive manager for Germany.

How to implement ads.txt on your site

Implementing ads.txt is remarkably simple. Follow these steps for effective implementation:

Create a text file named “ads.txt”
Contact your advertising partners to obtain their information
Structure the file according to the required syntax
Upload it to the root of your domain (e.g., www.yoursite.com/ads.txt)
Verify its accessibility and compliance

Moreover, several online tools allow you to validate your ads.txt file and identify potential errors:

“Implementing ads.txt increased our advertising revenue by 12% by reducing fraud and attracting premium bids from buyers who prioritize verified inventories.” – Jerome HENRY – AI & Marketing Consultant

Best practices and common errors

Essential recommendations

To maximize the effectiveness of your ads.txt file, follow these expert tips:

Publish OWNERDOMAIN even if it’s identical to your domain
Use MANAGERDOMAIN only for exclusive partners
Avoid conflicts between different MANAGERDOMAIN entries
Regularly update the file to reflect your current partnerships
Verify that DIRECT entries correspond to your direct accounts

Errors to avoid

Many publishers make these errors that compromise the effectiveness of ads.txt:

Inaccessible file: check permissions and access path
Incorrect syntax: strictly follow the required format
Outdated information: remove inactive partners
Duplicates: eliminate redundant entries
Poorly defined relationships: don’t confuse DIRECT and RESELLER

Impact of ads.txt on the advertising ecosystem

The massive adoption of ads.txt has profoundly transformed the digital advertising landscape. Its impact is manifested at several levels:

For publishers

Increased revenue: up to 15% increase observed
Reduced fraud: drastic decrease in domain spoofing
Enhanced transparency: clarified business relationships
Strengthened control: better management of sales channels

For buyers (DSPs)

Increased confidence: guarantee of impression authenticity
Optimized purchases: focus on verified inventories
Reduced risks: elimination of unauthorized sellers
Improved efficiency: better return on investment

For the global ecosystem

Standardization: adoption of a common standard
Cleanup: gradual elimination of fraudulent actors
Valuation: premium inventories better valued

The table below presents the results of a study on the impact of ads.txt on different advertising performance indicators:

Indicator	Sites with ads.txt	Sites without ads.txt	Difference
Average CPM price	$2.35	$1.89	+24.3%
Fraud rate	3.2%	11.7%	-72.6%
Fill rate	92.4%	84.1%	+9.9%
Click-through rate	0.42%	0.39%	+7.7%
Annual revenue	+15.2%	Reference	+15.2%

These figures clearly demonstrate the competitive advantage that implementing ads.txt brings to publishers.

The evolution of ads.txt: app-ads.txt and sellers.json

App-ads.txt for mobile applications

Following the success of ads.txt, the IAB developed app-ads.txt to extend these benefits to mobile applications. Conceptually identical, app-ads.txt adapts to the specificities of application stores.

Application developers must:

Declare an associated website in the app’s metadata
Publish an app-ads.txt file on this site

Sellers.json: the other face of transparency

If ads.txt allows publishers to declare their authorized sellers, sellers.json does the opposite: it allows exchange platforms to declare all their partner publishers.

“The combination of ads.txt and sellers.json creates a bilateral trust ecosystem. Publishers declare who can sell their inventory, and platforms confirm which publishers are their partners.” – Jerome HENRY – AI & Marketing Consultant

This complementary approach strengthens the fight against fraud and improves transparency throughout the supply chain.

How to verify the effectiveness of your implementation

To ensure that your ads.txt file is working correctly, perform these regular checks:

Test accessibility via a browser (yoursite.com/ads.txt)
Use specialized validators to detect errors
Check error logs in Google Ad Manager or similar platforms
Monitor your revenue to detect potential anomalies
Analyze invalidity reports provided by your partners

Major SSPs (Supply Side Platforms) and ad exchanges generally offer compliance reports that will help you identify potential problems with your ads.txt file.

Integration of ads.txt in a global anti-fraud strategy

Although extremely effective, ads.txt is just one element of a comprehensive anti-fraud strategy. For optimal protection, combine it with:

Sellers.json: reciprocal validation of business relationships
Supply Chain Object: complete traceability of the auction journey
Ads.cert: advanced cryptography to secure requests
Anti-fraud solutions: technologies for detecting suspicious behaviors
Regular audits: independent verifications of your inventory

This multi-layer approach ensures maximum protection against various forms of advertising fraud.

To further optimize your monetization strategy, it is essential to understand how quality content influences search results. Master semantic SEO and optimize your content for meaning and relevance. Discover techniques and tips to improve your positioning on Google. A solid semantic approach perfectly complements your ads.txt transparency approach.

The future of ads.txt and transparency standards

The success of ads.txt has paved the way for an increasingly transparent advertising ecosystem. Several developments are anticipated:

Reinforced integration with other standards (sellers.json, supply chain object)
Automation of verification and updating
Sectoral extensions for specific industries
Universal adoption as a prerequisite for programmatic transactions

These evolutions will continue to strengthen trust in the digital advertising ecosystem, benefiting all legitimate actors.

Domain Spoofing: How to Avoid Cyberattack Traps

Domain spoofing is a cyberattack technique where hackers create fake web domains or email addresses that closely resemble those of legitimate companies or organizations.

Also read: Windows 11 strengthens your cybersecurity with its advanced protection against password attacks and its new NTLM system.

The objective is to trick users into believing they are interacting with a trusted entity, when in reality they are being redirected to a fraudulent site or receiving malicious communications.

This malicious practice can take several forms:

Email spoofing: Attackers send emails that appear to come from a known and trusted sender.
Website spoofing: Cybercriminals create websites that mimic the appearance of legitimate sites, often using slightly modified domains (for example, by replacing similar characters).

Domain spoofing is frequently used in phishing attacks to steal sensitive information, distribute malware, or redirect users to unwanted sites.

This technique can also serve other malicious purposes, such as conducting distributed denial-of-service (DDoS) attacks or concealing the attackers’ identities.