ads.txt Validator
Make sure ad networks can read your ads.txt
Fetch or paste your ads.txt file and check every line for syntax errors, duplicates, wrong AdSense IDs and crawler access problems
Choose how to check
Enter your domain only. The tool requests /ads.txt on it.
Useful for checking a file before you upload it. Nothing is stored.
Add your publisher ID to confirm your own AdSense line is present and correct.
Checking…
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Valid records
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Direct / Reseller
ads.txt format reference
Each line in the file is one authorised seller, written as four comma-separated fields:
google.com, pub-0000000000000000, DIRECT, f08c47fec0942fa0
| Field | Name | What it means | Example |
|---|---|---|---|
| 1 | Ad system domain | The domain of the advertising system you sell through. | google.com |
| 2 | Publisher account ID | Your account ID inside that ad system. For AdSense it is pub- followed by 16 digits. | pub-0000000000000000 |
| 3 | Relationship | DIRECT if you own the account, RESELLER if another party may resell your inventory. | DIRECT |
| 4 | Certification authority ID | Optional. A TAG registry ID that identifies the ad system. Google's is f08c47fec0942fa0. | f08c47fec0942fa0 |
Lines starting with # are comments. The file can also contain variables such as CONTACT=, OWNERDOMAIN=, MANAGERDOMAIN= and SUBDOMAIN=.
Fix the file, then audit the whole site
ads.txt is one part of a monetisation-ready site. Run a complete audit to check speed, mobile-friendliness, meta tags and more.
Run Free Website AuditAbout ads.txt Validator
An ads.txt file is a public text file at the root of your website that lists the companies allowed to sell your ad space. Ad buyers and ad networks read it to avoid paying fraudulent sellers, and a missing or broken file can reduce the demand for your inventory. This tool fetches the file from your domain (or checks text you paste in), follows redirects, and checks every line against the IAB ads.txt syntax. It reports errors that make a line unusable, warnings such as duplicates and missing certification IDs, and server-side problems such as 404 responses, HTML pages served in place of the file, wrong content types and robots.txt rules that cover /ads.txt. If you enter your AdSense publisher ID, it also confirms that your own google.com line is present, marked DIRECT and carries the correct certification authority ID. You can export the parsed records as CSV or download a cleaned copy with invalid and duplicate lines removed.
Where should the ads.txt file be placed?
At the root of your domain, so it opens at example.com/ads.txt. Ad systems read the root domain’s file by default. Put the file in your public web folder, not inside a theme or subfolder.
What is my AdSense line?
Google shows it in your AdSense account under the ads.txt section. It follows the pattern google.com, pub-XXXXXXXXXXXXXXXX, DIRECT, f08c47fec0942fa0 with your own 16-digit ID. Paste your ID above to confirm it is in the file.
Should the relationship be DIRECT or RESELLER?
Use DIRECT when the account belongs to you or your company. Use RESELLER when the account belongs to someone else, such as an ad network that sells your space on your behalf.
Why does my file show HTML instead of text?
Many CMS and single-page-app setups answer every unknown address with their normal page. When /ads.txt has no real file behind it, you get a web page with a 200 status. Upload a real file named ads.txt to the web root.
Does a valid file guarantee that ads will serve?
No. This tool checks syntax and accessibility. It cannot confirm that your accounts are active or that an ad system has approved your site.