Why "title too long" is a useless thing to be told
Most on-page checkers hand you a red dot and a label. That leaves you to go and count the characters, look up the limit, and work out the fix yourself — which is the work you opened the tool to avoid.
Every check here reports the fact and the verdict separately. Not "title too long" but "63 characters, limit around 60", with the reason it matters. Problems sort to the top.
The one that silently deletes you from Google
An X-Robots-Tag: noindex HTTP header. There is nothing in the page
source to see — view-source tells you nothing, a browser extension cannot reach it,
and the page looks completely normal. A deploy sets it, or a staging config leaks into
production, and the page quietly stops being indexed. Because this audits from the
server side, it reads the response headers and catches it.
alt="" is not a missing alt
An empty alt attribute is a deliberate declaration that an image is decorative, and screen readers correctly skip it. Only an absent attribute is a failure. Plenty of audits conflate the two, which buries the handful of real problems under every spacer and icon on the page.
What it does not do
No JavaScript is executed. This reads the HTML your server actually sent, which is close to what a crawler that does not run scripts sees. If your headings are injected client-side they will not appear here — and that is itself worth knowing.