In a world where fraudulent ads run rampant, ads.txt has been created to bring control back to the honest buyers and sellers.
What is Ads.txt?
It is an IAB-approved text file that aims to prevent unauthorized inventory sales.
How does it work?
Publishers drop a text file on their web servers that lists all of the companies that are authorized to sell the publishers’ inventory. Similarly, programmatic platforms also integrate ads.txt files to confirm which publishers’ inventory they are authorized to sell. This allows buyers to check the validity of the inventory they purchase.
Ads.txt works by creating a publicly accessible record of authorized digital sellers for publisher inventory that programmatic buyers can index and reference if they wish to purchase inventory from authorized sellers. First, participating publishers must post their list of authorized sellers to their domain. Programmatic buyers can then crawl the web for publisher ads.txt files to create a list of authorized sellers for each participating publisher. Then programmatic buyers can create a filter to match their ads.txt list against the data provided in the OpenRTB bid request.
What’s included in an ads.txt file?
An ads.txt file contains a line for each authorized seller and each line includes up to four fields:
| Field | Name | Description |
| Field #1 | SSP/Exchange Domain | This field identifies the advertising system, like an SSP or exchange, that the buyers connect to. |
| Field #2 | SellerAccountID | This field includes the identifier associated with the seller or reseller account within the advertising system listed in field #1. |
| Field #3 | PaymentsType | This field indicates whether the inventory is being sold direct by the owner or through a reseller.‘DIRECT’ indicates that the publisher (content owner) directly controls the account indicated in field #2 on the system in field #1.
‘RESELLER’ indicates that the publisher has authorized another entity to control the account indicated in field #2 and resell their ad space via the system in field #1. |
| Field #4 | TAGID (Optional) | The current certification authority used is the Trustworthy Accountability Group (TAG). This field should list the TAGID that uniquely identifies the advertising system, named in field #1. Essentially, this is an additional level of security. |
Example: Example.com publishes ads.txt on their web server listing three exchanges as authorized to sell their inventory, including Example.com’s seller account IDs within each of those exchanges.
http://example.com/ads.txt:
#< SSP/Exchange Domain >, < SellerAccountID >, < PaymentsType >, < TAGID >
greenadexchange.com, 12345, DIRECT, AEC242
blueadexchange.com, 4536, DIRECT
silverssp.com, 9675, RESELLER
You can actually see the ads.txt file for publishers via their url. For example, see:
https://www.dailymail.co.uk/ads.txt
https://www.theguardian.com/ads.txt
How can buyers use ads.txt to check who is authorized to sell?
If an exchange and the pubs it represents each adopt ads.txt, bidders can check their tags for the presence of an ads.txt file to verify that the exchange and publisher have a legitimate connection to each other.
Essentially, if buyers are now able to see whether or not they are buying from an authorized seller of a publisher’s inventory through ads.txt. An agency that wants to buy from cnn.com via an exchange can actually verify that they are buying from cnn.com, not spoofedsite.com.
Potential Drawbacks
- Low adoption (although it has risen since Google has said that ads.txt will be the default setting of their bidder)
- Engineering resources to implement
- Exchanges/SSPs that rely on undisclosed selling may get burned.
What should buyers do?
Check to make sure that the inventory that they are buying is certified by ads.txt. Check the SSPs/Exchanges and all other sellers to make sure that they have ads.txt files that match the publishers whose inventory they are selling. Place filters to ensure that buys includes ads.txt certified inventory.
What should sellers do?
Publishers and all of their respective authorized sellers should ensure that they have ads.txt ready and implemented for buyers to filter against.
Sources
- https://digiday.com/marketing/wtf-ads-txt/
- https://iabtechlab.com/ads-txt-about/
- https://adexchanger.com/ad-exchange-news/google-strengthens-ads-txt-enforcement/
- https://www.spotx.tv/resources/blog/product-pulse/how-does-ads-txt-work/
Rather fail with honor than succeed by fraud.
— Sophocles
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