On-page SEO checker
Put in a URL and the tool loads the page and checks the things that affect ranking: title, description, headings, image alt text, canonical tag, robots meta, links and word count.
Fetched live, exactly as a crawler receives it.
What gets checked
Indexability
The tool checks meta robots and the canonical tag first, because nothing else matters if the page cannot be indexed. A noindex, or a canonical pointing at a different URL, takes the page out of search without any obvious sign.
Title and description
It checks whether they exist, how long they are in pixels and characters, and whether the title just repeats the H1. Missing and duplicate titles are the most common problems and the easiest to fix.
Structure
The page should have one H1 and a heading order that does not skip levels. Very short pages usually do not rank.
Media and links
Images without alt text do not show up in image search and are a problem for screen readers. The link counts show how the page links out and how much of that is nofollowed.