On-page SEO checker
Paste the full source code of a page (right-click, "view page source", select all, copy): the tool checks the on-page fundamentals and gives you concrete recommendations. Nothing is sent to a server.
To fix
To watch
Passed checks
These checks cover the fundamentals visible in the code of a single page. A full SEO audit also looks at crawling, internal linking, competitors and real-world performance.
What an on-page SEO checker does
An on-page SEO checker reads the code of a page and flags what to fix. This one checks the head tags (title, meta description, robots, canonical, language, viewport), the H1 to H6 heading structure and hierarchy, the volume of visible text, image alt attributes, internal and external links, Open Graph tags and JSON-LD structured data, including whether the JSON is valid. If you enter a target keyword, its presence is checked where it matters: title, H1, description and body copy.
Why paste the source code
For security reasons, a browser cannot go and read a page from another site. Rather than route your pages through a server, the tool asks for the source code: the analysis stays entirely local, including for staging pages or pages behind restricted access.
The limits of a static analysis
The tool reads the HTML as it is served. If your site generates part of its content in JavaScript, that content does not appear in the initial source code: the gap between the two is useful information in itself, since Google has to go through a rendering step to see it.