Sentence Case Fixer

WHAT IT DOES

Sentence Case Fixer is a browser extension that scans any webpage for incorrectly cased text and converts it to proper sentence case (first letter of each sentence capitalized, all other letters lowercase) while intelligently preserving proper nouns and acronyms. It detects sentences that are in all caps, all lowercase, or inconsistently cased, and applies the correct capitalization based on standard English punctuation rules. The tool preserves common proper nouns like "Google" and "January," acronyms like "AI" and "HTML," and brand names automatically. You can apply the fix to the entire page or only to selected text, with a live preview showing exactly what will change before you commit, and a full undo function to revert all changes instantly. The tool is ideal for writers, editors, content managers, and anyone who needs to ensure consistent sentence capitalization in web content.

WHERE IT RUNS

Sentence Case Fixer works on any webpage that contains text. It runs locally in your browser as a lightweight userscript, scanning text nodes across the entire page while avoiding script tags, style blocks, and form inputs. It works on blog posts, articles, documentation pages, email drafts, social media content, academic papers, and any other text-based content. The tool handles static pages, dynamically loaded content via AJAX, and single-page applications where content updates without page reloads. All processing occurs entirely in your browser—no text is ever sent to any server.

HOW TO USE

After installation, open the floating panel by clicking the extension icon. The panel automatically scans the page and shows a preview of all sentences that would be converted, with changes highlighted in green. Choose the scope using the dropdown menu: "Entire page" to apply to all text on the page, or "Selected text" to convert only the text you have highlighted. Enable or disable the "Preserve proper nouns and acronyms" toggle to control whether common proper nouns and acronyms are protected from lowercasing. Each change updates the preview in real time. Click the Preview button to refresh the preview display, the Apply button to commit the conversions to the page, and the Revert button to restore all text to its original state. The count display shows how many sentences have been or will be converted. All scope and preference settings are saved per domain.

REAL MECHANISM — WHY THIS WORKS

Most sentence case tools rely on simple word-level transformations that cannot distinguish between proper nouns, acronyms, and regular words, resulting in awkward lowercase acronyms and incorrect capitalization of brand names. Sentence Case Fixer uses a multi-stage sentence detection and case conversion engine. The engine first splits text into sentences using a finite-state machine that recognizes punctuation boundaries (. ! ?) while handling common edge cases such as abbreviations (Mr., Dr.), ellipsis (...), and decimal numbers. For each sentence, the engine tokenizes words while preserving whitespace and punctuation. It then applies the sentence case conversion: capitalizing the first letter of the first word and converting all other words to lowercase, unless the preserve-proper-nouns toggle is enabled. When enabled, the engine checks each word against a curated list of over 100 common proper nouns, acronyms, and brand names using case-insensitive matching. The engine also detects all-caps acronyms (e.g., "NASA," "API") by checking if a word consists entirely of uppercase letters and has at least two characters. Words that match these conditions are preserved in their original case. The preview mode uses a highlight mechanism that wraps converted text in styled spans, giving users a clear visual indication of what will change. This approach ensures accurate, context-aware sentence case conversion without sending any data off-device.

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 conversion options and statistics. Press the Escape key to close the panel instantly. The panel remains open across page navigation within the same domain, maintaining your current scope and preference settings. All preferences—panel position, scope selection, and proper-noun preservation toggle—are saved per domain for a seamless experience.

PLEASE NOTE

Sentence Case Fixer 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. Because websites frequently update their structure, scanning and conversion may require periodic script updates to maintain compatibility. If the tool does not convert text as expected, please check for updates or report the issue. All text processing occurs entirely in your browser. No page content, text samples, or conversion results are ever sent to any server. The extension does not read, store, or transmit any personal information. It only reads and modifies the DOM of the pages you choose to interact with, and all changes are fully reversible using the Revert function.