Before you can understand what an on-page SEO tool does, it helps to be precise about the term itself. On-page SEO refers to every optimization you make within a page's own HTML and content — as opposed to off-page signals like backlinks or technical infrastructure issues like server response times.
The elements on-page SEO covers include:
- Title tags — the clickable headline in search results
- Meta descriptions — the summary text below that headline
- Heading structure — H1 through H6 tags organizing the page's content
- Body copy — the actual text on the page, including keyword usage and topical depth
- Internal links — links pointing to other pages within your own site
- Image alt text — descriptive text attached to images for accessibility and crawlability
- Schema markup — structured data that helps search engines understand page context
- URL structure — the slug and path used to identify the page
On-page SEO is the layer you have direct, immediate control over. You don't need to earn a backlink or wait for a crawl cycle to update a title tag. That controllability is exactly why on-page optimization is typically where SEO work begins — and why the tooling category around it is so well developed.
One important distinction: on-page SEO is not the same as technical SEO. Technical SEO deals with site architecture, crawl budget, page speed, and indexability at the infrastructure level. On-page SEO assumes the page can be crawled and focuses on making its content as relevant and clear as possible for a target query.