Your ads.txt looks fine. Until DSPs check it.
Most validators check formatting. BeamFlow cross-references every ads.txt and app-ads.txt entry against 2,000+ live SSP sellers.json files. 24% of entries fail this check.
Free. No signup. Instant results.
Beyond syntax checking
Most validators check formatting. We check the supply chain.
Syntax & Format
Every line checked for correct field count, valid relationship types (DIRECT/RESELLER), properly formatted TAG IDs, and standard formatting.
sellers.json Verification
Each SSP domain and seller ID verified against the actual sellers.json file. We check if the seller ID exists and the seller type matches. This is what DSPs check.
Duplicate & Conflict Detection
Exact duplicates, near-duplicates (same SSP + ID, different relationship), and conflicting entries identified and flagged.
The revenue impact
Unverified entries cost you money. Every day.
When a DSP evaluates your inventory, it cross-references your ads.txt against the SSP's sellers.json. If the SSP doesn't list your seller ID, the DSP skips that supply path. No error. No notification. Bids just stop.
Our analysis of 362K+ publisher domains shows 24% of ads.txt entries fail sellers.json verification. For a publisher with 40 ads.txt lines, that's roughly 10 entries silently losing demand.
higher CPMs for verified supply paths
(Source: Index Exchange Research)
Seller ID not found in sellers.json
Relationship mismatch
The 6 most common ads.txt problems.
Based on analyzing 362K+ publisher domains.
Wrong account IDs
Your publisher ID doesn't match the SSP's records. Every DSP bid from that path gets rejected.
Stale entries
SSPs you no longer work with still in your file. Dead entries that give fraudsters masking opportunities.
Missing sellers.json match
The SSP doesn't list you in their sellers.json at all. Your authorized entry becomes unverifiable.
Duplicate lines
Same SSP and account ID listed multiple times. Wastes parser capacity and confuses strict DSPs.
Relationship type mismatch
Your ads.txt says DIRECT, but the SSP's sellers.json says INTERMEDIARY. Verification fails.
Syntax errors
Missing commas, wrong field order, curly quotes. The line can't be parsed by DSP crawlers.
How BeamFlow validates your ads.txt and app-ads.txt.
Fetch
We fetch your ads.txt and app-ads.txt directly from your domain.
Parse
Every line is parsed for syntax: SSP domain, account ID, relationship type, TAG ID.
Cross-reference
Each entry verified against the SSP's live sellers.json from our index of 2,000+ SSPs.
Report
Instant health score (A-F), color-coded line status, and prioritized fix recommendations.
ads.txt validator FAQ
Enter your domain above. BeamFlow fetches your ads.txt and cross-references every line against 2,000+ SSP sellers.json files. You get an instant health score and per-line status. Free, no signup.
Syntax checking confirms your ads.txt is formatted correctly. Verification confirms that the SSPs you listed actually recognize your account in their sellers.json. A line can have perfect syntax but fail verification.
An unverified entry means the SSP doesn't include your seller ID in their sellers.json file. This can happen because the SSP removed your account, your ID is incorrect, or the SSP hasn't updated their file.
Yes. When you enter your domain, BeamFlow checks both /ads.txt and /app-ads.txt automatically. The same sellers.json verification process applies to both files.
At minimum, quarterly. SSPs update sellers.json regularly. An entry that verified last month might fail today. For continuous protection, BeamFlow's Starter plan monitors daily and alerts you.
Yes. DSPs like Google DV360, The Trade Desk, and Amazon verify supply paths before bidding. If your ads.txt entry fails sellers.json verification, those DSPs skip your inventory. Verified supply earns up to 6x the CPM.
A 0-100 score combining syntax correctness, duplicate detection, and sellers.json verification. An 'A' grade (90+) means nearly all supply paths are verifiable. Below 70 means revenue is likely at risk.
The scan is free, no signup needed. You get a health score, sub-scores, and color-coded per-line status. For detailed fix instructions, monitoring, and multi-domain support, see our Starter plan at $49/mo.
Learn more about ads.txt
Common ads.txt Mistakes
The most frequent errors we find across 362K+ domains and how to fix them before they cost you revenue.
Read articleads.txt Best Practices
A practical guide to maintaining a clean, verified ads.txt file that maximizes demand from DSPs.
Read articleHow to Create an ads.txt File
Step-by-step instructions for creating, hosting, and validating your first ads.txt file.
Read articleFind out what DSPs see when they check your ads.txt.
Free validation. Instant results. No signup required.