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Site Audit

ads.txt Checker & Validator

Fetch a site’s ads.txt or app-ads.txt the way ad crawlers do, validate every line, check that your publisher ID is authorized and download a corrected file.

Runs on our serverUpdated
Add your publisher ID to check that it is authorized.

Enter a domain to check its ads.txt. Optionally add your AdSense publisher ID.

Enter any public URL above and press Enter or Ctrl + Enter.

  • Found / not found, with the redirect chain and content type
  • Every line validated: fields, relationship, certification ID, duplicates
  • Is your publisher ID authorized as DIRECT?
  • A corrected file to download, plus a live editor to re-check

This tool fetches the public URL you enter from our server. Results are held in temporary memory for a few minutes and never stored in a database.

How to use the ads.txt Checker

  1. Enter the domain where your ads run, e.g. example.com. Use the root domain: ad crawlers look for the file there.
  2. Optionally paste your AdSense publisher ID (pub-… or ca-pub-…) to check that it is authorized.
  3. Click Check. Pick app-ads.txt instead for mobile and connected-TV apps.
  4. Read the errors and warnings, then download the corrected file or edit it in place and click Re-check.

What does an ads.txt checker do?

ads.txt (Authorized Digital Sellers) is a public text file at the root of your domain listing the ad systems allowed to sell your ad space. Buyers check it before they bid, so a missing or broken file costs money: AdSense shows an “Earnings at risk” warning and some demand stops bidding. This tool fetches the file exactly where crawlers look for it and checks every line against the IAB ads.txt specification.

The record format

Each line has three or four comma-separated fields:

google.com, pub-1234567890123456, DIRECT, f08c47fec0942fa0
  1. Ad system domain — the exchange or network, e.g. google.com. A bare domain, not a URL.
  2. Account ID — your ID with that system. For Google it is pub- plus 16 digits (no ca-).
  3. Relationship — DIRECT if you own the account, RESELLER if someone else sells on your behalf.
  4. Certification authority ID (optional) — the system’s TAG ID; Google’s is f08c47fec0942fa0.

Lines may also be variables such as CONTACT=ads@example.com, SUBDOMAIN=blog.example.com, OWNERDOMAIN=example.com or MANAGERDOMAIN=network.com, and comments start with #.

Fixing “ads.txt not found” and “Earnings at risk”

  • Wrong place. The file must be at https://example.com/ads.txt — the root of the domain in your AdSense site list, not a subfolder.
  • www vs non-www. If your site lives on www.example.com but AdSense lists example.com, the root domain still needs to serve or redirect to the file.
  • An HTML page instead of text. Many CMSs answer unknown URLs with a 200 page; crawlers then read HTML as ads.txt and find no records.
  • Wrong publisher ID. Copy it from AdSense → Account → Settings → Account information, and drop the ca- prefix.
  • Just changed it? Google can take a few days to re-crawl ads.txt, so the warning can linger after the file is correct.

Need to create the file? Build one with the ads.txt Generator.

Also searched as: ads.txt validator, ads.txt not found, earnings at risk ads.txt, adsense ads.txt, app-ads.txt checker, ads.txt troubleshooter, verify ads.txt, authorized digital sellers.

Tools that pair well with the ads.txt Checker

  • Robots.txt Tester — Check whether a URL is allowed or blocked for Googlebot, Bingbot, GPTBot and other crawlers, see exactly which rule matched, and edit the file to test changes before you deploy them.
  • HTTP Header Checker — Fetch any URL and see exactly what the server sends back — status code, redirect chain and every response header, with a plain-English explanation of the ones that matter for SEO, caching and security.
  • Consent Mode Checker — Check a site’s cookie consent the way a regulator or an ad platform would.
  • robots.txt Explainer — robots.txt rules are short but easy to misread.

Frequently asked questions

Is ads.txt required for AdSense?
It is not required to be approved, but Google strongly recommends it. Without a correct ads.txt, AdSense shows an “Earnings at risk” warning and some buyers will not bid on your inventory.
Should my publisher ID start with ca-pub?
No. In ads.txt Google’s account ID is pub- plus 16 digits. The ca-pub- form is used only in the ad code.
What if I have no ads yet?
You can skip ads.txt — a missing file is normal. To state explicitly that nobody may sell your ad space, the IAB spec defines the line placeholder.example.com, placeholder, DIRECT, placeholder.
Can ads.txt redirect?
Yes. Crawlers follow redirects within the same root domain (for example http to https or to www), and the spec allows one redirect to a different domain, which ads.txt manager services use.
What is app-ads.txt?
The same format for mobile and CTV apps. It lives on the developer website listed in the app store, at /app-ads.txt.

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