Tips for avoiding common ads.txt problems
Our platform has tested thousands of ads.txt files. Here are some of the common issues we’ve seen.
Two weeks ago we launched AdstxtValidator.com to give ads.txt implementers (publishers, ad tech companies) a tool to ensure their files are compliant. Ads.txt adoption has been increasing, and our tool has been getting a lot of usage along the way. As ad technology goes, .txt looks to be the fasted in history (at least of IAB tech):
Our ads.txt testing and monitoring tool seems to be riding this wave of adoption, with thousands of unique ads.txt domains being tested through the platform in the first two weeks since launch:
Throughout this period, we’ve seen a striking percentage (~50%) of ads.txt files with 1 or more spec issues. Although this may be alarming to some (read: Digiday), it’s common to see issues when new standards are being adopted. Here are some tips to avoid some of the most common issues we’ve seen so far:
1. Make sure your ads.txt content type is text/plain
According to the actual IAB spec:
“The HTTP Content-type should be ‘text/plain’, and all other Content-types should be treated as an error and the content ignored.”
Translation: If your content type is wrong, it may be ignored altogether. Be sure to check for this when building/updating your file. To help you catch this, AdstxtValidator.com won’t even test your file if the content type is incorrect.
2. Don’t list more than 4 fields for a given record. If you have multiple IDs for a given domain, list each one as its own record.
3. Don’t forget your commas 😜
This is an easy mistake to make, especially if you have a lot of records. Make sure you run it through a validator after every change you make.
4. Don’t include Bidswitch in your ads.txt file
Bidswitch has confirmed that they should not be included in ads.txt files. They are neither an SSP nor a DSP.
5. If your ad partner isn’t a known exchange domain, ask them to share their preferred domain with the IAB
Some exchanges have not confirmed their canonical exchange domain with the IAB ads.txt working group. If you receive a warning like this, share it with your ad partner and request that they confirm their preferred domain name with the IAB. We mark this as a warning in the validator (not an error), so don’t worry too much. However, you should reach out to your partner and inform them that they aren’t listed.
6. Spell RESELLER correctly
Get Grammarly if you must 😂
7. Test early and often
For many publishers, your ads.txt file will be updated often. You may change the file to add/drop a new partner or to make a fix. For example here’s ESPN’s file over time:
If you think testing your file once is a good strategy, you’re opening your company up to future issues. Continuously monitor changes to your file to be certain you’re staying in spec.
8. Be careful who you add to your file!
There have been some instances (well documented) of partners trying to get publishers to add them to their file. If something feels fishy, dig deeper and ask for help before you blindly add them to your file. There are fantastic community resources out there who can help in situations like this (try the AdOps subeddit or AdOps Reddit Slack Group).
9. Don’t take your ad partner’s word for it
We’ve run into multiple cases where publishers have reached out to us telling us that their ad partners (big, reputable, vendors in the space) told them their ads.txt file was compliant, when in fact it wasn’t. Ads.txt is new to everyone, including even the biggest ad tech vendors. Plus, it’s not easy to keep up with changes to the IAB wiki, let alone remember all the specs when looking at a file. Don’t leave this up to human error, let computers do what they do best 🤓 Use a thirdparty validator to test against the specs.
We hope these tips will help you build and maintain valid ads.txt files. Happy TXTing!
