Ad fraud is a big problem in online advertising, with losses expected to double from 88 billion to 172 billion U.S. dollars by 2028, according to Statista.
As more ads are bought and sold automatically, the risk of scams—where ads are shown to bots instead of real people, for example—grows. In 2021, about 18% of ads shown this way in the U.S. were fake, which worries many marketers.
To fight this, the Interactive Advertising Bureau (IAB) introduced ads.txt. This simple solution helps publishers list who is allowed to sell their ad space, making it easier to avoid fraud.
Thus, understanding what ads.txt is, why it’s essential, and how to use it is vital for publishers, so that’s what we will present to you as simply as we can.
Table of contents
What Is Ads.txt?
Ads.txt (Authorized Digital Sellers) is an IAB-approved text file publishers use to list all the digital sellers they trust to sell their ad inventory.
Released in May 2017 as an initiative of IAB Tech Lab, these files are publicly crawlable by ad exchanges and SSPs. They aim to simplify the online advertising supply chain, ensure brands and advertisers can confidently purchase genuine digital media, and make it difficult for fraudsters to sell unauthorized inventory.
In mobile advertising, the equivalent of ads.txt is app-ads.txt. In a nutshell, ads.txt or app-ads.txt is utilized to:
- Identify who is authorized to sell publishers’ ad inventory.
- Allow buyers, ad exchanges, and others to crawl publishers’ domains.
- Match seller account IDs in bid requests.
- Protect advertisers from counterfeit ad inventory.
Where Is Ads.txt Located? But App-Ads.txt?
Publishers can find the ads.txt file in the root directory of their website at the top-level domain. Yet, since ads.txt is a public file, everyone who wants to verify if a publisher has an ads.txt file just must simply enter the following URL in the browser:
websitename.com/ads.txt
If the file is correctly placed, it will open and will look similar to the image we provided above in the example section.
For mobile advertising, publishers should place the app-ads.txt file in the root directory of their developer website. They must ensure that the domain of their app-ads.txt file matches the one listed in the app store (e.g., Apple App Store, Google Play Store). The URL will be:
websitename.com/app-ads.txt
How Does Ads.txt Work?
To use ads.txt, a publisher creates an ads.txt file containing details about all their programmatic partners (such as supply-side platforms, ad exchanges, and ad networks). As such, the file is then hosted on the publisher’s web server under their root domain.
Besides all the programmatic partners, the latest version of ads.txt/app-ads.txt, version 1.1, was released in August 2022 and introduced two new fields for publishers to declare within their ads.txt files: “OWNERDOMAIN” and “MANAGERDOMAIN.”
Once implemented, advertisers can easily access these ads.txt files online to see a list of authorized publishers and their ad inventory.
When an advertiser receives a bid request from a publisher, they can match the publisher’s account ID with the information in the ads.txt file. If the account ID matches, the advertiser knows the publisher is legitimate. If the ID does not match, the advertiser may choose not to bid on the publisher’s ad inventory.
This system benefits both advertisers and publishers. It reduces the risk of advertisers’ inventory appearing on low-quality or fraudulent websites and helps publishers ensure they work only with reputable ad exchanges and ad networks.
Ads.txt Example Explained
Let’s take a more visual and well-explained example. For instance, Coindoo’s ads.txt file which is available at https://www.coindoo.com/ads.txt.
In examining the Coindoo ads.txt file, each line typically contains 3 or 4 parameters separated by commas.
- Field #1 (Required): Domain Name of SSP/Exchange
#SEVIO adx.ws, 510f8f3e-1af3-445d-894b-232dbe93c65d, DIRECT #sevio.com
This is the Supply-Side Platform (SSP) domain name or exchange authorized to sell or resell the publisher’s ad inventory. Examples include adx.ws, google.com, pubmatic.com, and blocknow.com, based on our visual example provided above.
- Field #2 (Required): Publisher’s Account ID
#SEVIO adx.ws, 510f8f3e-1af3-445d-894b-232dbe93c65d, DIRECT #sevio.com
This unique identifier corresponds to the publisher’s account within the SSP or exchange listed in Field #1. It ensures transactions are correctly attributed to the publisher. Examples of IDs include 510f8f3e-1af3-445d-894b-232dbe93c65d, pub-2134012267069721, 164776, 99066753ed19303816.
- Field #3 (Required): Relationship Type (DIRECT or RESELLER)
#SEVIO adx.ws, 510f8f3e-1af3-445d-894b-232dbe93c65d, DIRECT #sevio.com
This field specifies how the publisher interacts with the SSP or exchange listed in Field #1:
- DIRECT – The publisher directly controls and manages their ad inventory through the SSP or exchange.
- RESELLER – The publisher has authorized a third-party entity to manage and sell their ad inventory on their behalf.
- Field #4 (Optional): Trustworthy Accountability Group (TAG) ID or Certification Authority ID
google.com, pub-2134012267069721, DIRECT, f08c47fec0942fa0
This optional field contains an identifier if the SSP or exchange has registered with the TAG. TAG certification helps verify that the entity adheres to industry standards for transparency and fraud prevention. Examples of TAG IDs include f08c47fec0942fa0, 5d62403b186f2ace.
In the example provided, the first entry under #SEVIO indicates that ads can be sold through adx.ws, with 510f8f3e-1af3-445d-894b-232dbe93c65d serving as SEVIO’s unique account identifier. The term DIRECT specifies that SEVIO directly manages its relationship with adx.ws, maintaining full control over their ad inventory sales. The comment #sevio.com further clarifies SEVIO’s affiliation.
Moving to #Google, the file lists google.com as an authorized platform with pub-2134012267069721 as the publisher’s account ID. Here, DIRECT signifies that the publisher has a direct relationship with Google, overseeing the sale of their ad space. The additional identifier f08c47fec0942fa0 is a TAG ID, ensuring Google’s compliance with industry standards.
In the case of #PubMatic, the file shows two entries for pubmatic.com. The first entry designates a RESELLER relationship, meaning PubMatic is authorized to resell the publisher’s ad inventory using account ID 164776. The second entry, also with account ID 164776, indicates a DIRECT relationship, signifying that the publisher retains direct control over this segment of their inventory. The TAG ID 5d62403b186f2ace enhances transparency by verifying PubMatic’s legitimacy.
Lastly, #Blocknow is identified as an authorized reseller through blocknow.com, with 99066753ed19303816 as the associated account ID. This RESELLER relationship allows Blocknow to sell the publisher’s ad inventory on their behalf.
Additionally, the file specifies management and ownership domains: MANAGERDOMAIN=sevio.com indicates SEVIO manages the ad inventory, while OWNERDOMAIN=coindoo.com denotes Coindoo as the owner of the ad inventory.
Why Is Ads.txt Important
Ads.txt is important because it tackles a tough problem in online advertising: fake sellers. It’s like a “do not duplicate” list for ad space. Websites use this simple file to clearly state which companies are allowed to sell ads on their site. This cuts down on shady characters pretending to be someone else and stealing ad revenue.
The benefits are clear. Advertisers know exactly who they’re dealing with, so they’re not tricked into paying for fake ads. Publishers keep their ad income safe from imposters. It’s a win-win for a cleaner and more trustworthy online advertising industry.
To help you understand better, we will explain how online advertising worked before and after the implementation of ads.txt.
Before Ads.txt
In the early days of online advertising, things were booming. From blogs to big news sites, website owners saw a way to make money by offering ad space on their pages. Advertisers eager to reach new customers were happy to pay for these spots. It was a perfect setup – publishers got paid, and advertisers found new people to buy their products.
But, as with any good thing, troublemakers showed up. These digital scammers saw a chance to make a quick buck by taking advantage of the loose rules in online advertising. They figured out how to pretend to be real websites.
Here’s how it worked: These scammers created fake websites that looked just like popular or well-respected ones. Then, they’d contact advertisers, claiming to be the real website and offering great ad placements for cheap. Advertisers, excited about reaching a lot of people, would jump at the chance without realizing they were buying ad space on fake storefronts.
The whole thing was a mess. Publishers, the ones who deserved the ad money, got cheated, and the money advertisers paid went straight into the pockets of these fakers. But the worst part was the loss of trust.
Without a way to tell the real websites from the fakes, the whole online advertising system became suspicious. Advertisers were scared to spend money because they worried about getting ripped off. Publishers couldn’t find real advertisers to pay for their ad space, so their income dried up. The once-thriving online advertising world turned into a gamble where everyone lost.
Then, in 2017, at the initiative of IAB, came ads.txt, a simple tool that cleaned things up a little. This file allowed website owners to say out loud who could sell their ad space. This transparency cleared the air and gave advertisers a way to check if a seller was real before spending their money.
After Ads.txt
With ads.txt in place, trust started to come back.
Publishers, no longer worried about being cheated, could focus on building their online businesses, knowing their ad money was safe.
Advertisers, with less fear of getting scammed, could confidently invest their budgets, knowing their ads were reaching real people on real websites.
The story of ads.txt shows that even small changes can make a big difference. It turned the Wild West of online advertising into a more organized system where both publishers and advertisers can succeed. It’s a reminder that even with big problems, a smart idea can fix things and create a brighter future for everyone.
Is Ads.txt Mandatory?
Ads.txt is not universally mandatory, but its adoption among publishers has grown significantly since its release in May 2017. Initially, uptake was slower than expected, with various reports indicating low adoption rates. For instance, as of August 2017, a study by MarTech Today showed that only 34 out of the top 500 (6.8%) most trafficked sites had implemented ads.txt.
However, the landscape has shifted, with major publishers increasingly embracing the initiative. Google’s endorsement has also been pivotal, influencing more platforms to integrate ads.txt requirements.
While ads.txt isn’t mandatory across the board, its benefits are clear, and that’s why some platforms, like Sevio Ad Manager, have made ads.txt mandatory to uphold inventory integrity. Related to Sevio Ad Manager, although currently required for desktop inventory, plans are in place to extend this requirement to app inventory in the future.
How to Implement Ads.txt: Step-by-Step with the Easiest Ways
There are several ways to implement ads.txt. We will present you with two options, the easiest and most commonly used ones:
- Implement ads.txt using a WordPress plugin;
- Implement ads.txt by adding it directly to the root folder.
1. Implement Ads.txt Using a WordPress Plugin: Step-by-Step Guide
Step 1. Access Your WordPress Dashboard and Go to the Plugins Section
To add ads.txt to your WordPress site, start by logging in to your WordPress admin dashboard.
Once you’re logged in, navigate to the Plugins section located on the left-hand side menu. Within the Plugins section, click on Add New Plugin. This will take you to the plugin installation screen.
Step 2. Search, Install, and Activate the Ads.txt Manager Plugin
In the search bar, type “Ads.txt Manager” and press enter. Locate the Ads.txt Manager plugin in the search results and click Install Now. After installation is complete, click Activate to enable the plugin.
Step 3. Navigate to the Ads.txt Settings to Configure It
With the Ads.txt Manager plugin activated, a new menu option will appear on your dashboard: Settings > Ads.txt. Click on this option to configure your ads.txt settings.
In the specified field, you are required to enter the data. If you are using Sevio Ad Manager and configuring your website inventory, you will find an Ads.txt section. Here, you can locate the text that needs to be inserted into the Ads.txt Manager plugin on your WordPress website.
More details here.
2. Implement Ads.txt by Adding It Directly to the Root Folder: Step-by-Step Guide
Step 1. Log In to Your Hosting Service Dashboard and Access File Manager
Begin by logging in to your web hosting service’s control panel. Once logged in, locate the section for managing your website’s files. This is often labeled as File Manager, File Management, or something similar.
Step 2. Click on Public_html and Press the Upload Button
Within the File Manager, locate and click on the folder containing your website’s core files. This is typically named public_html. Once you’ve accessed your website’s root directory, look for an Upload button or functionality.
Step 3. Upload Your Ads.txt File
Use this feature to select and upload the ads.txt file you’ve created beforehand. Ensure the file is uploaded to the root directory itself, not within any subfolders.
If you’re utilizing Sevio Ad Manager, the Ads.txt file can be automatically generated from our platform. As you configure your website inventory, you’ll encounter an Ads.txt section where you can access the file. You’ll need to download it and then upload it to the root directory of your website.
More details here.
Final Thoughts
While ads.txt won’t eliminate all fraud in the adtech industry, it addresses a major problem and sets the stage for a more transparent online advertising environment.
This tool encourages honesty and actively combats ad fraud and unethical practices.
As more companies seek methods to fight ad fraud, we anticipate that many will increasingly embrace this move toward transparency in the future (if they haven’t already).
Was this helpful?
