What is Ads.txt and Why It Matters: A Beginner’s Overview

In the past, the digital advertising Programmatic industry has faced significant challenges with ad fraud, where unauthorized sellers exploit the system to their advantage. This fraudulent activity not only undermines trust between publishers and advertisers but also leads to financial losses. However, in response to these concerns, the introduction of Ads.txt has played a crucial role in combating ad fraud and enhancing transparency within the advertising supply chain. Ads.txt, a simple yet effective text file, empowers publishers to publicly list authorized sellers of their ad inventory, mitigating the risks of unauthorized reselling and ensuring a safer and more trustworthy advertising ecosystem.

What is Ads.txt?

Ads.txt, short for Authorized Digital Sellers, is an initiative developed by the IAB Tech Lab to combat ad fraud and bring transparency to the online advertising industry. Released in May 2017, this project aims to tackle domain spoofing and illegitimate inventory arbitrage, ensuring that brands and advertisers can purchase authentic digital media with confidence.

By using a text file called ads.txt, publishers can publicly list authorized sellers of their ad inventory, thereby preventing fraudulent instances of unauthorized inventory sales. This file allows ad buyers to validate sellers and avoid unauthorized traffic sales. Essentially, ads.txt acts as a trust mechanism, enabling potential media buyers to verify ad sellers and ensure high-quality impressions. 

Who invented Ads.txt and its version?

Ads.txt was introduced by the IAB Tech Lab, a non-profit organization, in 2017 to address the issue of ad fraud in the digital advertising industry. The initial version of Ads.txt was released in March 2017 and was known as version 1.0.3. Over time, improvements and updates were made, and the current version of Ads.txt is version 1.1, which was launched in April 2022.

The main purpose of Ads.txt is to combat ad fraud by allowing publishers to publicly list the companies they authorize to sell their ad inventory. This transparency makes it harder for fraudsters to sell counterfeit inventory since buyers can easily verify the legitimacy of the seller. By having this authorized list of sellers, publishers can maintain control over their ad inventory and ensure that it is sold through legitimate channels.

Since its introduction, Ads.txt has gained widespread adoption among publishers, including well-known websites like The New York Times, The Wall Street Journal, and CNN. It has become an industry standard and is estimated to cover over 80% of all ad inventory as of 2021.

The success of Ads.txt has also inspired the development of other initiatives to combat ad fraud. One such initiative is the App-ads.txt standard, created by the IAB Tech Lab, which focuses on addressing ad fraud in mobile apps. Additionally, the Trustworthy Accountability Group’s (TAG) Publisher Verification Program offers publishers a way to verify their inventory and prevent ad fraud, further strengthening the fight against fraudulent practices in the digital advertising ecosystem.

How Ads.txt Works

Ads.txt works by providing a public record of authorized sellers for a publisher’s ad inventory. Publishers create a text file called Ads.txt and list the companies that are authorized to sell their ads. When a buyer wants to purchase ad space from a publisher, they can check the Ads.txt file to verify if the seller is authorized. If the seller is not listed, it raises a red flag that the inventory may be fake or fraudulent.

The Ads.txt file acts as a trust mechanism, ensuring transparency and preventing ad fraud. By publicly listing authorized sellers, it becomes more challenging for fraudsters to sell counterfeit inventory because buyers can easily confirm the legitimacy of the seller. This helps maintain the integrity of the online advertising ecosystem and protects both publishers and advertisers.

How Ads.txt Solves Problems

Ads.txt effectively addresses several problems related to ad fraud. It tackles issues such as:

• Domain Spoofing: Fraudsters create fake websites that mimic legitimate publishers, tricking buyers into purchasing ad space on these fake sites. Ads.txt mitigates this problem by allowing buyers to verify if the seller is listed in the publisher’s Ads.txt file. If the seller is not authorized, it indicates the inventory is fake.
• Unauthorized Inventory Sales: Fraudsters may try to sell ad inventory they don’t have the rights to, leading to wasted ad spend. Ads.txt helps combat this issue by providing a trusted list of authorized sellers. Buyers can ensure they are purchasing inventory from legitimate sources.
• Unauthorized Inventory Sales: Fraudsters may try to sell ad inventory they don’t have the rights to, leading to wasted ad spend. Ads.txt helps combat this issue by providing a trusted list of authorized sellers. Buyers can ensure they are purchasing inventory from legitimate sources.
• Low-Quality Inventory: Fraudsters may sell ad inventory that is of poor quality, resulting in ineffective ad campaigns. Ads.txt helps prevent this by enabling buyers to verify sellers and avoid purchasing low-quality inventory. This ensures that advertisers get the value they expect from their ad spend

Understanding Different Types of Ads.txt Files

Ads.txt: Ensuring Transparency in Website Advertising

Ads.txt is a powerful tool that brings transparency to the world of online advertising. It is a text file created by publishers to publicly list the authorized companies that can sell their ad inventory on websites. This simple yet effective measure helps combat ad fraud and protect advertisers from falling victim to counterfeit inventory sales.

App-ads.txt: Safeguarding Mobile App Advertising

With the rise of mobile apps, ad fraud has extended its reach into this domain. To address this issue, publishers utilize App-ads.txt. This specific type of Ads.txt file allows them to list authorized companies permitted to sell their ad inventory within mobile apps. By implementing App-ads.txt, publishers can safeguard their mobile app advertising and establish a trusted environment for both advertisers and users.

Private Marketplace (PMP) Ads.txt: Protecting Ad Inventory in Exclusive Marketplaces

Private marketplaces offer an exclusive environment for publishers and advertisers to conduct business. To maintain the integrity of these marketplaces, publishers employ PMP Ads.txt. This specialized Ads.txt file enables publishers to list authorized companies that have permission to sell their ad inventory within private marketplaces. By doing so, publishers can ensure that only trusted partners have access to their premium inventory, minimizing the risk of fraudulent activities.

Supply Chain Object (SCO) Ads.txt: Enhancing Transparency Across the Advertising Supply Chain

The advertising supply chain can be complex, with multiple intermediaries involved in the buying and selling of ad inventory. To promote transparency and combat fraud within supply chain objects, publishers utilize SCO Ads.txt. This unique Ads.txt file allows publishers to list authorized companies that are involved in the supply chain and have permission to sell their ad inventory. By implementing SCO Ads.txt, publishers can monitor and control the flow of their inventory, reducing the risk of fraudulent activities at various stages of the supply chain.

How to Read Ads.txt and Ads.txt 1.1?

Reading Ads.txt is a straightforward process. The file consists of lines, each representing a record of a company authorized to sell ad inventory on a specific domain. These lines are structured with the following information:

Domain: The publisher’s domain name.

Name: The authorized company’s name for selling ad inventory on the domain.

ID: A unique identification number assigned by the publisher to the company.

Relationship: The type of relationship between the publisher and the company, either “DIRECT” or “RESELLER”.

For instance, consider this line: example.com, Google, pub-123456789012345, DIRECT. This line indicates that “Google” has direct authorization from the publisher to sell ad inventory on the “example.com” domain.

Example of an Ads.txt file

example.com, Google, pub-123456789012345, DIRECT

example.com, AppNexus, pub-123456789012345, RESELLER

example.com, Rubicon Project, pub-123456789012345, DIRECT

In this example, “Google,” “AppNexus,” and “Rubicon Project” are authorized to sell ad inventory on the “example.com” domain. “Google” has direct authorization, while “AppNexus” and “Rubicon Project” are authorized as resellers.

Ads.txt 1.1 introduced an additional field

TAG ID: A unique identifier assigned by the Trustworthy Accountability Group (TAG) to verify companies meeting transparency and accountability standards.

Example of an Ads.txt File

For example: example.com, Google, pub-123456789012345, DIRECT, ca-pub-123456789012345. In this case, “Google” has direct authorization from the publisher, and the TAG ID “ca-pub-123456789012345” confirms the company’s adherence to TAG’s standards.

Understanding the structure and information within Ads.txt and Ads.txt 1.1 files is essential for publishers, advertisers, and other stakeholders in the digital advertising ecosystem. These files enable transparency, combat ad fraud, and establish trust among the parties involved.

How to Create an Ads.txt File

Creating an Ads.txt file is a simple process that involves adding authorized sellers to a text file. By following a few steps, you can create and maintain an effective Ads.txt file for your website. Here’s a step-by-step guide:

• Step 1: Open a Text Editor: Start by opening a blank text file using a plain text editor like Notepad (for Windows) or TextEdit (for Mac).
• Step 2: Add Authorized Seller Information: Each line of the Ads.txt file represents an authorized seller. Add the following four pieces of information for each seller, separating them with commas:

Domain: Your publisher’s domain name.

Name: The authorized company’s name for selling ad inventory on your domain.

ID: A unique identification number assigned by you to the company.

Relationship: Specify the relationship with the authorized company, whether “DIRECT” or “RESELLER”.

• Step 3: Repeat for Additional Sellers: If you have more than one authorized seller, start a new line in the file and repeat Step 2 for each additional seller.
• Step 4: Include Other Sellers (Optional): If you want to authorize sellers other than Google, you can add their information manually. Simply ask each demand partner for the complete line to be added to your Ads.txt file.
• Step 5: Save and Upload:Save the text file with the name “ads.txt” and upload it to the root directory of your website. The root directory is the folder following the top-level domain (e.g., example.com/ads.txt).

Building an Ads.txt File with Google AdSense

If you use Google AdSense, the process becomes even easier. AdSense provides a downloadable ads.txt file with Google listed as an authorized seller. Here’s how to get started:

Sign in to your AdSense account and navigate to the “Sites” section.

Find the option to “Create an ads.txt file for…” and click it.

Download the ads.txt file that includes Google as an authorized seller.

Manually add any other authorized sellers to the file if needed.

Save the file and upload it to your website’s root directory.

Adding Ads.txt to Different Platforms: A Step-by-Step Guide

How to add Ads.txt to WordPress?

To add Ads.txt to your WordPress website, follow these steps:

Log in to your WordPress admin dashboard.

Install and activate a plugin that allows you to edit your site’s header or add custom code, such as “Header and Footer Scripts” or “Insert Headers and Footers.”

Go to the plugin’s settings or options page.

Locate the section for adding code to the header.

Open a new tab or window and access your Ads.txt file. Copy the entire content of the file.

Return to the plugin settings and paste the Ads.txt content into the header code box.

Save the changes.

Verify that the Ads.txt file is properly added by visiting “https://yourdomain.com/ads.txt” in your web browser. Make sure you replace “yourdomain.com” with your actual domain.

How to add Ads.txt to Google AdSense

To add Ads.txt to your Google AdSense account, follow these steps:

Sign in to your AdSense account.

Click on “Sites” in the left-hand menu.

Find the site for which you want to add Ads.txt and click on it.

Click on “Fix now” if there is an alert regarding Ads.txt, or click on “More” and select “Manage ads.txt” for the respective site.

Click on “Copy” to copy the provided Ads.txt line.

Open a new text file in a plain text editor, paste the line, and save it as “ads.txt”.

Upload the “ads.txt” file to the root directory of your website.

Verify that the file is correctly added by visiting “https://yourdomain.com/ads.txt” in your browser.

How to add Ads.txt to Google Ad Manager?

To add Ads.txt to your Google Ad Manager account, follow these steps:

Sign in to your Google Ad Manager account.

Click on “Admin” and select “Global settings”.

Scroll down to the “Inventory” section and click on “Ads.txt” settings.

Click on “New ads.txt rule”.

Enter your domain name and paste the authorized seller information in the provided fields.

Save the settings.

Verify that the Ads.txt file is properly added by visiting “https://yourdomain.com/ads.txt” in your browser.

Adding Ads.txt to Blogger

How to add Ads.txt to your Blogger website?

Log in to your Blogger account and select the blog where you want to add Ads.txt.

Go to the “Settings” menu and click on “Search preferences”.

Under the “Monetization” section, locate “Custom ads.txt” and click on “Edit”.

Open a new tab or window and access your Ads.txt file. Copy the entire content.

Return to the Blogger settings and paste the Ads.txt content into the provided box.

Save the changes.

Verify that the Ads.txt file is properly added by visiting “https://yourdomain.com/ads.txt” in your browser.

How to add Ads.txt to Squarespace?

To add Ads.txt to your Squarespace website, follow these steps:

Log in to your Squarespace account and navigate to the website you want to edit.

Go to the “Settings” menu and click on “Advanced”.

Under the “Code Injection” section, locate the “Header” field.

Open a new tab or window and access your Ads.txt file. Copy the entire content.

Return to the Squarespace settings and paste the Ads.txt content into the “Header” field.

Save the changes.

Verify that the Ads.txt file is properly added by visiting “https://yourdomain.com/ads.txt” in your browser.

Verifying Ads.txt: Ensuring Accuracy in Your Ad Inventory

How to Verify Ads.txt?

Verifying your Ads.txt file is a crucial step to ensure it is working correctly and providing the transparency needed to combat ad fraud. Here are some effective methods to verify your Ads.txt:

• Ads.txt Validator: Utilize the Ads.txt Validator, available at https://adstxt.guru/validator/. This tool will automatically check your Ads.txt file for errors and ensure it is correctly formatted, saving you time and effort.
• Google AdSense Ads.txt Verification Tool: If you use Google AdSense, you can employ their Ads.txt Verification Tool, accessible at https://support.google.com/adsense/answer/12171612?hl=en. This tool validates your file’s compatibility with Google AdSense and ensures that it meets the required standards.
• Manual Check: Manually inspect the contents of your Ads.txt file to verify its accuracy. It should contain a comprehensive list of authorized sellers for your domain, with each entry specifying the seller’s domain name, publisher ID, and relationship type (either “DIRECT” or “RESELLER”).

By utilizing these verification methods, you can be confident that your Ads.txt file is in place, correctly listing authorized sellers, and providing the transparency needed to protect your ad inventory from fraudulent activities.

Steps to Verify Ads.txt

Verifying your Ads.txt file is a simple process. Follow these steps to ensure its accuracy:

Create the Ads.txt File: Develop an Ads.txt file containing the necessary information, such as the seller’s domain name, publisher ID, and the relationship type (either “DIRECT” or “RESELLER”).

Upload the File: Upload the Ads.txt file to the root directory of your website or app. Placing it in the root directory ensures easy access for verification.

Use Verification Tools: Employ helpful verification tools like the Ads.txt Validator or Google AdSense Ads.txt Verification Tool. These tools will automatically review your file, check for errors, and confirm compatibility.

Check for Errors: If any errors or discrepancies are identified, review and correct them in your Ads.txt file. Properly formatted and accurate files ensure transparency in your advertising ecosystem.

Successful Verification: Once the verification tools indicate that your Ads.txt file is error-free and properly formatted, you have successfully verified your file.

The Power of Ads.txt: Empowering Publishers and Advertisers

Advantages of Ads.txt for Publishers:

1. Increased Transparency: Ads.txt provides publishers with a powerful tool to publicly list authorized sellers of their ad inventory. This added transparency safeguards publishers from unauthorized reselling and ad fraud, ensuring a more secure ad ecosystem.
2. Improved Ad Quality: With Ads.txt, publishers can enhance the quality of ads served on their websites and apps. By listing authorized sellers, advertisers are more likely to bid on this inventory, leading to better-targeted and higher-quality ad placements.
3. Increased Revenue: Ads.txt empowers publishers to maximize their revenue by ensuring they only sell ad inventory to authorized sellers. This proactive approach prevents ad fraud and safeguards publishers’ earnings from potential losses.

Advantages of Ads.txt for Advertisers:

1. Increased Confidence: Ads.txt instills confidence in advertisers by enabling them to verify the legitimacy of the ad inventory they purchase. The public listing of authorized sellers gives advertisers reassurance that their investments are in the right hands.
2. Reduced Risk of Fraud: Ads.txt acts as a robust defense against ad fraud by making it challenging for fraudulent sellers to peddle unauthorized ad inventory. This shields advertisers from financial losses due to fraudulent activities.
3. Improved Ad Quality: With Ads.txt, advertisers benefit from improved ad quality. They can target their desired audience with greater precision, resulting in more relevant ad placements and better-performing advertising campaigns.
4. Enhanced Brand Safety: By collaborating exclusively with authorized sellers, Ads.txt ensures that advertisers’ ads are displayed on reputable websites. This safeguards their brand reputation by avoiding associations with malicious or inappropriate content.
5. Optimized ROI: With Ads.txt, advertisers can confidently invest their advertising budgets in high-quality impressions from authorized sellers. This strategic approach optimizes their return on investment (ROI) and maximizes campaign success.

Ads.txt for Mobile Apps( app-ads.txt): Safeguarding App Inventory and Enhancing Ad Quality

Ads.txt has proven to be an effective tool for safeguarding publishers’ ad inventory and combating ad fraud in the web domain. For mobile apps, the same principle is applied through a file called app-ads.txt, specifically designed to protect mobile apps from unauthorized reselling and fraudulent activities.

The app-ads.txt file, located in the root directory of the app’s bundle, serves as a comprehensive list of authorized sellers for the app’s ad inventory. Each entry contains crucial information such as the seller’s domain name, publisher ID, and the nature of the relationship with the publisher (direct, reseller, or unknown).

Benefits of App-ads.txt:

1. Increased Transparency: App-ads.txt offers publishers a means to publicly list authorized sellers for their mobile app inventory, fostering transparency and trust in the ecosystem. This ensures that ad space is not sold to unauthorized sellers, safeguarding the app’s reputation.

2. Improved Ad Quality: By implementing app-ads.txt, mobile app developers can attract higher-quality advertisers. Advertisers are more likely to bid on ad inventory listed in app-ads.txt, resulting in better-targeted and more relevant ad placements.

3. Increased Revenue: App-ads.txt empowers publishers to maximize their revenue by exclusively selling ad inventory to authorized sellers. Preventing ad fraud ensures that potential revenue losses are mitigated.

If you are a mobile app publisher, it is highly recommended to create and upload an app-ads.txt file to your app’s root directory. This simple step can protect your app from ad fraud and elevate the overall quality of ads displayed within your app.

Ads.txt and Ads.cert: Enhancing Security and Transparency in Digital Advertising

Feature	Ads.txt	Ads.cert
Purpose	To help publishers protect their ad inventory from unauthorized reselling and ad fraud.	To provide additional security and transparency for the digital ad supply chain.
How it works	Ads.txt is a text file that lists the authorized sellers of a publisher’s ad inventory.	Ads.cert is a cryptographically signed file that provides additional security for the digital ad supply chain.
	Advertisers can use Ads.txt to verify that the ad inventory they are buying is legitimate.	Advertisers can use Ads.cert to verify that the bid requests they are receiving are legitimate.
Pros	– Easy to implement. – Widely adopted. – Free to use.	– Provides additional security. – Addresses some of the limitations of Ads.txt.
Cons	– Can be easily spoofed. – Does not provide full transparency.	– Not yet widely adopted. – More complex to implement.

Which one should you use Ads.txt vs Ads.cert?

If you are seeking a straightforward and easy-to-implement solution to safeguard your ad inventory from unauthorized reselling and ad fraud, Ads.txt is a viable choice. It is widely adopted, simple to use, and cost-effective. However, if you prioritize enhanced security and aim to address some of the limitations of Ads.txt, Ads.cert may be the better option, despite its more complex implementation.

The Future of Ads.txt and Ads.cert

To further enhance the security and efficacy of both Ads.txt and Ads.cert, the IAB Tech Lab is actively working on a new standard known as Ads.txt v2. This upcoming version will leverage cryptographic signatures to verify the authenticity of entries in the file, making it significantly more challenging for attackers to spoof Ads.txt files and sell unauthorized ad inventory. This advancement will bolster the industry’s ability to combat ad fraud and provide even greater transparency in the digital ad supply chain. As the digital advertising landscape continues to evolve, Ads.txt and Ads.cert remain crucial tools in promoting trust and security for both publishers and advertisers.

In conclusion, the research and studies conducted on Ads.txt provide valuable insights into its adoption and impact on the digital advertising landscape. The longitudinal analysis by Muhammad Ahmad Bashir et al. demonstrates that Ads.txt has been widely embraced by publishers, leading to a reduction in unauthorized ad inventory within the supply chain. Additionally, the study by Clearcode highlights the positive effect of Ads.txt in mitigating ad fraud, albeit acknowledging that it cannot completely eliminate it.

Furthermore, the research conducted by DoubleVerify emphasizes the effectiveness of Ads.txt in combatting domain spoofing, further solidifying its role in safeguarding publishers from unauthorized reselling and fraudulent activities. These findings underscore the importance of Ads.txt as a valuable tool for promoting transparency and trust in the digital advertising ecosystem.

However, it is crucial to recognize that Ads.txt is not a one-size-fits-all solution and should be complemented with other security measures to bolster protection against ad fraud. As the digital advertising landscape continues to evolve, the industry must continue to innovate and develop strategies to enhance the efficacy of Ads.txt and further strengthen the fight against unauthorized activities.

In summary, the studies on Ads.txt highlight its significance in the fight against ad fraud and underscore the need for continuous improvements to ensure a more secure and transparent advertising environment for publishers and advertisers alike.