Is there a good free tool to analyze the optimization of an article ?

I'm a copywriter (and programmer), and before I make the classic programmer move and spent days creating a tool for analyzing my articles, I'm trying to find one that already exists and that is free. But all the ones I found so far are exponentially worse than the paid ones, like Semrush google docs extension.

I'm looking at some Github projects, but all of them ( like lighthouse) seem to be focused more on other SEO aspects besides the content (text/article) which is what i actually need.