What tool can I use to increase ONPAGE score?

for example, I heard that if you put in the table of contents / mark, the online score will go up.

Share Twitter Function what elese is there?

there are plenty of blog posts, threads & videos about this,
make a research then feel free to answer questions

Anything that 1) makes it easier for search engines to understand what your content is about, and 2) enhances the user experience will inevitably improve your On-Page score regardless of the tool you use.

There is plenty of literature out there that recommends pretty much the same when it comes to On-Page SEO.

Even on this forum, there are some great threads about it.

For example...

https://www.blackhatworld.com/seo/guide-full-example-of-how-to-do-on-page-seo.1251425/https://www.blackhatworld.com/seo/q...c-with-a-little-research-on-page-seo.1240147/
From outside the forum, these are some of the resources I´ve bookmarked that cover this topic...

https://ahrefs.com/blog/on-page-seo/https://backlinko.com/seo-checklisthttps://www.kalungi.com/blog/a-complete-guide-to-on-page-seo-2021-checklisthttps://www.matthewwoodward.co.uk/seo/on-page/checklist/
And my own personal favorites...

https://www.gotchseo.com/on-page-seo/https://seosly.com/on-page-seo-checklist/
If that´s under the "tl,dr" category, I am going to give you some stuff to focus on besides the basics like...

* include Your Keyword In Your URL
* Use Short URLs
* Front-Load Your Keyword In Your Title Tag
* Embed Title Tag Modifiers
* Use Your Keyword Once In The First 150 Words
* Use Your Keyword in H1, H2 or H3 Tags

Instead, I am going to tell you to heavily focus on these On-Page factors...

https://www.searchenginejournal.com/ranking-factors-sejebook-download/
That is one of the most comprehensive lists you´ll find on the internet about On-Page SEO and what is consider to be a ranking factor.

Personally, I will heavily recommend you to focus on elements like...

* Internal links
* Anchor text - Contextual are better
* Core Web Vitals / Page Speed
* Mobile-Friendliness
* Unique, high-quality, and engaging content
* HTTPS
* User-Generated Content

Hope this helps, cheers!

Work on your site speed, it will help tot increase your site score