In 2007, MediaMath launched the first platform, TerminalOne, that purchased online ads using real time auctions. Since then the programmatic ecosystem and underlying technologies have grown and flourished such that a decade later in 2017, programmatic display spending reached almost $33 billion globally with 80% of display advertising in the US now being transacted programmatically.


Fraud, however, is a huge concern for the industry with an estimated $6.5 billion or roughly 20% being based on fraudulent activity in 2017. Much of this fraud is inventory purporting to be from genuine sites being sold on programmatic exchanges. To test the level of fraudulent inventory, News UK switched off their programmatic inventory supply for 2 hours in December 2017 and discovered the monthly equivalent of £750,000-£1m worth of bogus inventory being sold in the name of The Sun and The Times on a single exchange.


Ads.txt (Authorized Digital Sellers)


To help combat inventory fraud, in May 2017 the IAB introduced a simple but powerful standard called ads.txt. This standard specifies a simple, flexible and secure method that publishers and distributors can use to publicly declare the companies they authorize to sell their digital inventory. In more detail, the publisher places a short text file called ads.txt in the root of their domain listing the exchanges and accounts on those exchanges which are authorised to sell their inventory. Buyers can then verify for each bid request received whether or not the bid request is referring to real or fraudulent inventory.


An example ads.txt file is shown below:

google.com, pub-6085868767790033, DIRECT
indexexchange.com, 692913, DIRECT
appnexus.com, 5803, DIRECT


This file indicates that the publisher sells programmatic inventory directly only on 3 exchanges (Google’s AdX, Index Exchange and AppNexus) under the accounts listed. Any inventory appearing on other exchanges or accounts can then be considered to be fraudulent.


The adoption of ads.txt was slow to begin with. In September 2017, just 8.5% of the top 5,000 websites worldwide selling programmatic ads had deployed ads.txt. However, by the end of February 2018, more than half of these sites were using ads.txt and of the publishers that are integrated into the SmartMatch platform, 90% have already adopted ads.txt.


Exchanges are now starting to throw their weight behind the standard. Since November 8th, publishers that use ads.txt on Google’s AdX exchange are protected against unauthorized inventory being sold in their auctions and other exchanges are sure to follow suit.


Smartology’s Implementation


We at Smartology are committed to reducing fraud and increasing trust in the programmatic space and in January 2018 added full ads.txt support to our SmartMatch programmatic bidder.

Our SmartMatch bidder now repeatedly scans ads.txt from all our integrated publishers and, where ads.txt exists, will only bid on inventory where the exchange and account information in the incoming bid requests match what’s been declared in their ads.txt.


Future Developments


Ads.txt doesn’t solve all of the fraudulent inventory issues in programmatic. As ads.txt adoption and enforcement is increasing, resellers are naturally keen to have their entries in those files. However, with reselling, the publisher is one step removed from the delivery of inventory and therefore bad actors can use reselling to inject bogus inventory into the ecosystem. To solve this issue, additional mechanisms are required to ensure that the inventory is as it is claimed.


The IAB are currently in the process of defining OpenRTB 3.0 and part of that standard will be ability for publishers and exchanges to sign the key parts of a bid request, with those key parts being domain, publisher id, bundle id and source IP address. This will enable buyers to both authenticate the source of the inventory and guarantee that the bid request has not been modified en route.  The public key required to verify the signature can be obtained from a file called ads.cert which will also be in the root of the publisher or exchange’s domain.

We’ll be closely following these developments to ensure that SmartMatch is up-to-date with the latest in fraud prevention technology.




These IAB standards will help in the ongoing efforts to combat ad fraud with ads.txt providing the authorisation and ads.cert the authentication of the source of bid requests. With SmartMatch, advertisers and publishers are further protected as we only match against genuine content through carefully selected publisher partners. Our bidder checks and verifies the domain of incoming bid requests and is configured to only profile content from trusted sources.





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