What is a technical SEO checker?
A technical SEO checker reads a page the way a search engine does and tests the parts that decide whether it can be found, understood and shown well. It looks at the reply the server gives, the rules that allow or block indexing, and the tags in the page.
It suits a quick check of a new page, a page that dropped in search, or a template after a release.
What does it check?
Indexing: the status code, redirects, noindex in the page or in the headers, and robots.txt rules. Signals: the canonical, hreflang language tags, the title, the meta description and the H1 to H6 outline.
Sharing and safety: Open Graph and Twitter tags for link previews, security headers, caching and compression. Mobile: the viewport, font size and tap targets.
Which problems matter most?
Anything that stops indexing comes first: an error status, a noindex tag left from a test site, a robots.txt block or a canonical that points somewhere else. These can take a page out of search on their own.
Weak titles, missing descriptions and messy headings come next. They don't block a page, but they make it less likely to be clicked.
One page or the whole site?
This checker looks at one page in depth. Website Audit runs the same checks on every page of the site and groups problems that come from one template, so you fix them once.