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ads.txt Validator

Paste any ads.txt or app-ads.txt file and check every line for errors.

How to use the validator

Paste the full contents of your ads.txt or app-ads.txt file into the box. The validator checks every line as you type and lists only the lines with errors or warnings, with a plain-language explanation for each. Tick Show every line to see the whole file with line numbers. Enter your Google publisher ID to confirm that a valid google.com line exists for it. The example already in the box contains deliberate mistakes so you can see how the report looks.

What it checks

  • Record structure: each record needs at least three comma-separated fields (ad system domain, account ID, relationship) and at most four, the fourth being a certification authority ID.
  • Ad system domain: must be a valid domain without “http://”, and normally without “www.”.
  • Relationship: must be DIRECT or RESELLER.
  • Google lines: the account ID must be “pub-” followed by 16 digits, and the certification ID should be f08c47fec0942fa0.
  • Duplicates: repeated records are flagged so you can tidy the file.
  • Variables: CONTACT, SUBDOMAIN, INVENTORYPARTNERDOMAIN, OWNERDOMAIN and MANAGERDOMAIN are recognised; anything else is flagged.
  • Comments and blank lines: text after # is ignored, as the standard requires.

Errors vs warnings

An error means ad systems will probably ignore that line, for example a misspelled relationship or a malformed publisher ID. A warning means the line is likely to work but is not best practice, such as a duplicate or a missing certification ID. Fix errors first.

Validate a live file

To test the file that is actually on your website, including the HTTP status and redirects, use our ads.txt checker. To build a new file from scratch, use the ads.txt generator.

Privacy

The validator runs entirely in your browser. What you paste is not sent to our server.

Frequently asked questions

Does the validator work for app-ads.txt?

Yes. app-ads.txt uses the same format as ads.txt, so the same checks apply.

Why is a missing certification ID only a warning?

The fourth field is optional in the standard. Google recommends including its ID, f08c47fec0942fa0, so the validator reminds you.

Is the validator an official Google tool?

No. It checks your file against the IAB Tech Lab ads.txt format and Google’s published line format. Your ad network’s own report is the final word.

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