Word counter.

The counts are the obvious part: words, characters with and without spaces, sentences, paragraphs, and an estimated reading time based on 225 words per minute, which is roughly the average for adult reading on screen.

The keyword density panel is the part worth your attention. It strips out stop words and shows which terms you actually repeat, ranked. Two things usually show up. Either your target keyword barely appears, which means the page is about something other than what you intended. Or it appears far too often, which reads as strain to a human and as manipulation to a search engine.

There is no magic percentage. Modern search engines understand synonyms and context, so the old advice about hitting 2% density is obsolete and following it produces stilted copy. What still holds: your main topic should appear naturally in the first paragraph, in at least one heading, and often enough elsewhere that a reader could tell you the subject without being told.

Worth knowing

• Meta descriptions fit around 155 characters, title tags around 60. Draft here, then check the pixel width in the SERP preview.
• If your main keyword is not in the top five by density, the page probably reads as being about something else.
• Reading time is a solid proxy for whether a blog post is worth splitting into two.