Flashing Content Blocker

WHAT IT DOES

Flashing Content Blocker is a browser extension that detects and blocks flashing or strobing content on any webpage. It identifies elements with rapid animation or opacity changes that could trigger photosensitive reactions, migraines, or discomfort. The tool applies CSS overrides to stop flashing animations and transitions, and provides visual indicators showing which elements have been blocked. Users can toggle the feature on or off and adjust the sensitivity level (1-100) to control how aggressively content is blocked. The tool is ideal for users with photosensitive epilepsy, vestibular disorders, migraines, or anyone who experiences discomfort from flashing content on websites.

WHERE IT RUNS

Flashing Content Blocker 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, scanning the DOM for flashing elements and applying CSS overrides. 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 blocker. Adjust the sensitivity slider to control how easily the tool detects flashing content—lower values detect more subtle flashing, higher values only detect more intense flashing. The panel shows the number of blocked elements. Click the "Scan Now" button to manually scan the page for flashing content. Click the "Clear Blocks" button to remove all blocking and unblock elements. The tool automatically scans periodically and watches for dynamically added content. All settings are saved per website.

REAL MECHANISM — WHY THIS WORKS

Most flashing detection tools rely on simple pattern matching or external analysis. Flashing Content Blocker uses a comprehensive scoring system that analyzes multiple factors to identify flashing content. The tool examines CSS animation and transition properties, checking for short durations (under 0.5 seconds) that indicate rapid changes, animation names containing flash-related keywords (flash, blink, pulse, flicker, strobe), and opacity or color changes. Each factor contributes to a flash score, and if the score exceeds the sensitivity threshold, the element is blocked. The tool then generates unique CSS selectors for each blocked element and applies !important rules that override animation, transition, opacity, and visibility properties to stop the flashing. A visual indicator (red outline with a warning label) is added to blocked elements. The tool scans every 3 seconds and uses a MutationObserver to detect dynamically added content. This approach ensures accurate, real-time, and fully private flashing content detection and blocking 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 controls. 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, enabled state, and sensitivity—are saved per domain for a seamless experience.

PLEASE NOTE

Flashing Content Blocker 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 uses a scoring system based on animation properties; some flashing content may not be detected if it uses non-standard methods (e.g., JavaScript-driven animations). The sensitivity setting adjusts the detection threshold; lower values may block more elements, including some that are not truly flashing. The tool does not block video or GIF content, only CSS-based animations and transitions. All settings are stored locally in your browser using GM_setValue. No page content, detection data, or usage information is ever sent to any server. The extension does not read, store, or transmit any personal information. It only scans and modifies CSS at your request.