Ads.txt Toolkit

Ads.txt (Authorized Digital Sellers) is an IAB Tech Lab initiative that helps prevent unauthorized inventory sales and domain spoofing. It's a text file that lists all companies authorized to sell your ad inventory, ensuring transparency in programmatic advertising and protecting your revenue from fraudulent activities.

The ads.txt file must be placed in the root directory of your website, accessible at https://yourdomain.com/ads.txt. Ad exchanges and platforms will look for it at this exact location to verify authorized sellers.

DIRECT indicates a direct business relationship between the publisher and the advertising system. RESELLER indicates the publisher has an indirect relationship, where another entity manages the inventory. Use DIRECT when you have a direct account with the ad network, and RESELLER when working through intermediaries.

The certification authority ID (also called TAG-ID) is an optional fourth parameter that identifies the advertising system within a certification authority. For Google AdSense, this is typically a 16-character hexadecimal string. Including it helps verify the authenticity of the business relationship.

Use the Validate mode in this toolkit to check your ads.txt file for syntax errors, format issues, and compliance with IAB standards. The validator checks for proper formatting, valid account types, domain formats, and provides warnings for missing certification IDs.

Yes, you can have multiple entries for the same domain with different publisher IDs or account types. This is common when you have multiple accounts with the same ad network or use both DIRECT and RESELLER relationships. However, avoid exact duplicates as they provide no additional value.

Update your ads.txt file whenever you add or remove advertising partners, change business relationships, or modify publisher IDs. Regular reviews (monthly or quarterly) are recommended to ensure accuracy and remove outdated entries that could affect your ad revenue.

Errors in your ads.txt file can lead to rejected ad requests, reduced fill rates, and lost revenue. Ad exchanges may not recognize improperly formatted entries, potentially blocking legitimate advertising relationships. Use this toolkit's validator to identify and fix errors before deploying.

Yes, you can add comments by starting a line with the # character. Comments are useful for organizing your entries, adding notes about specific partnerships, or documenting when entries were added. Comments are ignored by ad exchanges when parsing the file.

While not strictly required, having an ads.txt file is highly recommended even for AdSense-only publishers. It prevents unauthorized reselling of your inventory and may improve your standing with ad networks. Simply include your AdSense publisher ID with DIRECT as the account type.

The Analyze mode provides insights into your ad inventory distribution, showing the balance between DIRECT and RESELLER relationships, unique ad partners, and potential duplicate entries. This helps you identify opportunities to optimize relationships, remove outdated entries, and ensure your inventory is properly managed.

Save your ads.txt file as plain text (UTF-8 encoding) with the filename "ads.txt" (all lowercase). Do not use .doc, .docx, or other formats. The file should be served with the content-type "text/plain" from your web server.