Keyword Density Analyzer - Private In-Browser SEO Checker

What it does: shows how often each word and phrase appears in a text and whether your target keywords are used too little, just right, or too much. Paste plain text, a Markdown draft, or the HTML of a page, it counts the real words and skips markup, code, and links.

Who it is for: SEO writers, bloggers, and content marketers who check a draft before publishing, and site owners and agencies who want their own private keyword density checker on their site or inside their tools.

What you get: a ready one-page tool you can upload to any static host (no server, no database, no API key), a reusable JavaScript module with the analysis that works in a browser or Node.js, 20 unit tests, and HTML documentation.

What you do: upload the keyword-density-analyzer folder to your host, or open it with any local web server. Paste a text. Change texts, colors, the good density range, or the stop words in one place each, as the documentation shows.

Features

• Runs fully in the browser. The text never leaves the page, a strict Content-Security-Policy blocks every network request.
• Text, Markdown, or HTML input with automatic detection, scripts, styles, code, tags, and URLs are removed before counting.
• Words, unique words, sentences, characters, characters without spaces, and reading time.
• Top 20 one-word, two-word, and three-word phrases with count and density. Phrases never cross the end of a sentence or line.
• Target keywords with a level: missing, too low (under 1%), good (1-3%), too high (over 3%).
• Plural forms counted together (tool and tools, story and stories), switchable.
• English stop words hidden from the lists, switchable, they always count in the total.
• Any language: Unicode words, apostrophes inside words kept.
• Download the results as CSV or copy them as text.
• Light and dark theme, works on phones, keyboard friendly.

Screenshots

Documentation: https://keyword-density-analyzer.pages.dev/docs/