What Is ads.txt?
ads.txt stands for Authorized Digital Sellers. It’s a simple text file that you publish on your website to list which companies are allowed to sell ads on your behalf. The reason it exists is trust: without a public seller list, bad actors can try to spoof inventory by claiming they’re authorized to sell impressions on your domain. ads.txt helps buyers and ad systems verify that the seller relationship is real.
When you publish a clean ads.txt, ad platforms can crawl it and confirm your authorized sellers. This can reduce invalid traffic issues, improve transparency, and prevent revenue loss caused by unauthorized reselling. For many publishers, it’s also a basic requirement to keep ad serving healthy across partners.
Where ads.txt Lives on Your Site
The ads.txt file must be publicly accessible at the root of your domain. That means a URL like https://yourdomain.com/ads.txt. If your site uses “www” and your traffic is there, you may also want to ensure that https://www.yourdomain.com/ads.txt resolves correctly, depending on how your canonical and redirects are configured.
If you serve ads on subdomains, you may need a separate ads.txt for each subdomain that runs ads. Some setups also use redirects, but the safest approach is to publish directly at the correct root location for the domain that serves the ads.
ads.txt Line Format Explained
Each line in ads.txt describes one authorized seller relationship. The usual structure is:
ad_system_domain, publisher_account_id, relationship_type, certification_authority_id
The certification authority ID is optional in the standard, but many systems (especially Google) include it. The most important thing is accuracy: the domain and account ID must match what your partner provides, and the relationship type must be correct.
DIRECT vs RESELLER: How to Choose
DIRECT means you control the account relationship with the ad system for that inventory. If you have your own account and you’re monetizing directly, DIRECT is usually correct. RESELLER means another entity is selling your inventory through their account—common with some managed services or intermediaries.
Choosing incorrectly can cause mismatches. If a platform expects RESELLER and you publish DIRECT, it may treat the entry as invalid. When in doubt, use the values and relationship type supplied by your ad partner.
Why Keeping ads.txt Updated Matters
ads.txt isn’t “set once and forget.” Partners change, accounts change, and monetization setups evolve. If you add a new network and forget to add their ads.txt line, that partner may have trouble selling or reporting correctly. If you remove a partner and keep their entries forever, the file can become cluttered and harder to audit.
A good habit is to keep your ads.txt organized with comments and update it whenever you change monetization partners. This generator helps you build clean output quickly, but maintenance is still part of running a site.
How to Use This ads.txt Generator
Start by entering your domain. Then add each partner as a separate entry: ad system domain (for example, google.com), your publisher account ID, the relationship type, and the CA ID if provided. If you enable comments, the generator will also add simple labels that make your file easier to read later.
Once you add entries, generate the output and copy or download your ads.txt file. Finally, upload it to your site root. After publishing, give platforms time to crawl it, then check dashboards for ads.txt status messages.
How to Validate an Existing ads.txt
The Validate tab is useful when you inherit a file or want to sanity-check formatting. Paste your ads.txt and the tool
will look for common issues: missing fields, invalid relationship type, stray commas, or lines that appear malformed.
It also ignores comment lines that start with #.
Validation isn’t a substitute for partner documentation, but it’s a fast way to catch errors that can break crawling. A single typo—like an extra comma or an incorrect DIRECT/RESELLER value—can cause the line to be ignored.
Common Mistakes to Avoid
- Wrong account ID: using an ID from another property or old account.
- Wrong relationship type: DIRECT vs RESELLER mismatch.
- Publishing in the wrong place: not at the domain root.
- Formatting typos: stray commas, missing fields, or invisible characters.
- Overcrowding: keeping outdated partners forever without cleanup.
ads.txt vs app-ads.txt
ads.txt is for web inventory. app-ads.txt is for mobile apps and is published on the developer website domain, pointing to the app’s authorized sellers. If you run both web and app monetization, you may need both files, each in the correct location and format for its ecosystem.
Safe Use Notes
This generator formats entries correctly, but it cannot know your true partner relationships. Always use the exact values provided by each ad system or mediation partner, and follow their instructions for DIRECT/RESELLER and CA IDs. After publishing, check your ad platform dashboards for ads.txt errors or “not found” warnings.
FAQ
ads.txt Generator – Frequently Asked Questions
Answers about ads.txt format, where to publish it, DIRECT vs RESELLER, comments, validation, and crawling time.
ads.txt (Authorized Digital Sellers) is a text file published on your domain that lists the ad systems allowed to sell your inventory. It helps reduce spoofing and unauthorized reselling.
You publish it at the root of your domain, like: https://example.com/ads.txt. Most ad platforms require it to be publicly accessible.
A standard line has: ad_system_domain, publisher_account_id, relationship_type, certification_authority_id (optional). Example: google.com, pub-0000000000000000, DIRECT, f08c47fec0942fa0
DIRECT means you have a direct account relationship with the ad system for that inventory. RESELLER means another entity is authorized to resell your inventory through that ad system.
Usually, ads.txt applies to the domain it’s hosted on. If you serve ads on subdomains, you may need an ads.txt on the subdomain as well depending on your setup and partners.
It can take hours to days depending on ad systems and crawlers. After publishing, wait and re-check in your ad platform dashboards for status updates.
Yes. ads.txt supports comment lines that start with #. Comments are useful for labeling sections or noting where an entry came from.
No. It generates correctly formatted entries, but you must use the exact values provided by your ad partners and follow their documentation.
app-ads.txt is for mobile apps and is hosted on the developer’s website domain. ads.txt is for web inventory on a site.