Timestamp trust = content-changed URLs / lastmod-changed URLs. If your build stamps today on every URL but only a handful changed, the indexer recrawls, finds nothing, and demotes the whole file. A false freshness signal is worse than none.
Your score and verdict appear here.
Why lastmod is the signal you probably lie with
Real-time AI indexers lean on lastmod harder than Google does, because freshness is the strongest scheduling input they have. The failure is quiet: a build that stamps today on all 12,000 URLs tells the indexer everything changed, it recrawls, finds nothing changed on thousands of pages, and demotes the recrawl priority of the entire file. Timestamp trust is the ratio that catches this before the indexer does, content-changed URLs over lastmod-changed URLs. Fix a low score with hash-based lastmod: write a new timestamp only when the rendered body actually changes.
How to use it
- Count how many URLs got a new lastmod in your last build, usually the whole file if you build-stamp.
- Count how many URLs genuinely changed content, from a content-hash comparison or your CMS.
- Read the ratio: 0.7 and above is trustworthy, 0.2 to 0.7 is an engineering ticket, below 0.2 means you should publish no lastmod at all.
- If the score is low, switch to hash-based lastmod so timestamps only move when content moves.
What is a good timestamp trust score?
1.0 means every timestamp change was a real content change. Aim for 0.9 or above. Below 0.7 is an engineering ticket, and below 0.2 you are better off publishing no lastmod, because an absent signal is neutral while a false one is penalised.
How do I stop build-stamping every URL?
Hash the rendered body of each page with the volatile regions stripped, nav, footer, build IDs and rendered timestamps, compare against the stored hash, and write a new lastmod only when the hash differs. The article includes a Python implementation.
Is it better to omit lastmod than to get it wrong?
Yes, once trust drops below roughly 0.2. An absent lastmod is a neutral signal the indexer ignores, whereas a timestamp it has learned to distrust actively demotes your recrawl priority. Honest and present beats frequent and false.
Does this tool send my numbers anywhere?
No. The ratio is computed entirely in your browser. Nothing you enter is uploaded or stored.