What this SEO checker looks at
It reads the page's HTML the way a search engine does and checks the things that decide whether Google can find, understand and show it: the title, the meta description, headings, the canonical tag, indexing rules (robots meta tag, X-Robots-Tag and robots.txt), images, links, structured data, social tags, mobile setup, language, HTTPS and how fast the server answers.
Every finding comes with what it means and what to change. Red items stop a page from ranking, amber items cost you clicks, and grey items are nice to have.
How the score works
The score starts at 100. Each serious problem takes off 14 points, each warning 6, and each small suggestion 2. It's a quick way to compare pages and see progress, not a number Google uses.
A page can score well and still not rank if the content doesn't match what people search for. That's where real search data helps: connect Google Search Console in Clarnic to see which searches each page appears for.
What it can't see
This check reads one page's HTML. It doesn't run the page's JavaScript, so content added only by scripts won't be counted. It also can't see your rankings, clicks or backlinks.