Ads.txt Validator
Validate ads.txt files against IAB specifications
What is Ads.txt?
Ads.txt (Authorized Digital Sellers) is an IAB Tech Lab initiative that helps ensure the authenticity of digital ad inventory. Publishers create a publicly accessible ads.txt file that lists all companies authorized to sell their inventory, helping prevent unauthorized inventory sales and domain spoofing.
Ads.txt Format
domain, publisher_id, relationship, [certification_id]
domain: The domain of the advertising system (e.g., google.com)
publisher_id: Your account ID with that system
relationship: Either DIRECT or RESELLER
certification_id: Optional TAG certification authority ID
Frequently Asked Questions
What is the purpose of ads.txt?
Ads.txt helps publishers prevent domain spoofing and unauthorized inventory sales by publicly listing authorized sellers.
What is the difference between DIRECT and RESELLER?
DIRECT indicates the publisher works directly with the ad system. RESELLER indicates the publisher has authorized another entity to sell their inventory through that system.
Where should I host my ads.txt file?
Ads.txt must be hosted at the root level of your domain (e.g., example.com/ads.txt).
Common Errors
Missing Required Fields
Each entry must have at least domain, publisher_id, and relationship
Invalid Relationship Value
Relationship must be exactly "DIRECT" or "RESELLER" (case-insensitive)
Malformed Domain
Domain must be a valid domain name without protocol (no http://)