Readability Score Checker

WHAT IT DOES

Readability Score Checker is a browser extension that analyzes the text content of any webpage and calculates readability scores including Flesch Reading Ease, Flesch-Kincaid Grade Level, and Gunning Fog Index. It displays each score with color-coded indicators (green for good, yellow for moderate, red for difficult) and provides a plain-language interpretation of what each score means. The tool also shows word count, sentence count, syllable count, and number of complex words. It is ideal for writers, editors, content creators, students, and anyone who wants to assess the readability of web content and ensure it is appropriate for their target audience.

WHERE IT RUNS

Readability Score Checker runs on any webpage, overlaying a floating panel that does not interfere with page content. It operates entirely in your browser as a lightweight userscript, extracting text content from the page and running readability calculations. It works on any page, whether static or dynamic, with no external dependencies. All settings are stored locally using GM_setValue—no data is ever sent to any server.

HOW TO USE

After installation, open the floating panel by clicking the extension icon. The panel shows the current status (Enabled or Disabled) and a toggle button to enable or disable the checker. The panel displays readability scores with color-coded indicators: Flesch Reading Ease (0-100, higher is better), Flesch-Kincaid Grade Level (lower is better), and Gunning Fog Index (lower is better). Each score includes an interpretation, e.g., "Very easy (5th grade)" for Flesch Reading Ease. The panel also shows word count, sentence count, syllable count, and complex word count. Click the "Refresh" button to manually update the display. The tool automatically updates when the page content changes. All settings are saved per website.

REAL MECHANISM — WHY THIS WORKS

Most readability tools require copying and pasting text into an external website or using complex natural language processing libraries. Readability Score Checker uses a lightweight, in-browser approach that extracts text directly from the page and calculates readability scores using well-established formulas. The tool extracts visible text from the page using a TreeWalker, excluding script and style elements. It then counts words, sentences, and syllables using a syllable counting algorithm with common exceptions. The Flesch Reading Ease formula uses: 206.835 - 1.015 * (words/sentences) - 84.6 * (syllables/words). The Flesch-Kincaid Grade Level uses: 0.39 * (words/sentences) + 11.8 * (syllables/words) - 15.59. The Gunning Fog Index uses: 0.4 * ((words/sentences) + 100 * (complex words/words)). Each score is displayed with a color-coded indicator and a plain-language interpretation. This approach ensures accurate, fast, and fully private readability analysis without requiring any external services or network access.

THE PANEL

The floating panel is fully draggable and remembers its position per site, snapping to the edges of the viewport when dragged near them. You can collapse the panel to a small icon to minimize screen distraction and expand it back with a single click. The panel is resizable from the bottom-right corner, giving you more space to view the results. Press the Escape key to close the panel instantly. The panel remains open across page navigation within the same domain, maintaining your current view state. All preferences—panel position and enabled state—are saved per domain for a seamless experience.

PLEASE NOTE

Readability Score Checker requires the free BotGentz extension to be installed and enabled, as it relies on the cross-extension messaging API provided by BotGentz for DOM access permissions. The tool analyzes visible text content only; it does not read hidden or dynamically loaded content that is not in the DOM. Syllable counting uses a heuristic algorithm and may not be 100% accurate for all words. The readability scores are calculated based on standard English formulas and may not be appropriate for all types of content. All settings are stored locally in your browser using GM_setValue. No page content, text data, or usage information is ever sent to any server. The extension does not read, store, or transmit any personal information. It only analyzes text content locally at your request.