Refererer by Libor Benes

• Designed for web developers, security researchers, privacy enthusiasts, educators, and students to monitor HTTP Referer headers in real-time.
• Captures URLs with their Referer headers for all web requests, providing an intuitive interface to debug navigation patterns, analyze Referer leaks, or learn about HTTP headers.
• Copy output using Ctrl+A, Ctrl+C, or right-click for analysis in external tools.
• Bold Referer lines, making them easy to distinguish from URLs.
• Auto-scrolls to the latest entry.

Prioritizes security, user safety, and browser integrity, adhering to Mozilla’s standards:
• Minimal Permissions, no unnecessary access to sensitive browser features or user data.
• No Data Collection: Processes headers locally within the browser, with no data stored or transmitted externally, ensuring complete privacy.
• Local Operation: Does not initiate external network requests or rely on APIs/servers. All processing (capturing headers, storing in browser.storage.local, rendering in the sidebar) occurs locally, allowing the add-on to function without external connectivity. Note: Header capture requires active web browsing, as it monitors user-initiated requests.
• Safe DOM Manipulation: Avoids risky methods to prevent vulnerabilities.
• No Third-Party Libraries: Built with pure JavaScript, HTML, and CSS, eliminating dependency vulnerabilities and reducing the attack surface.
• Robust Error Handling.
• Storage Security: temporarily stores headers, with no persistent storage of sensitive data.

User Precautions:
• Referer Leaks: Be aware that Referer headers may contain sensitive information (e.g., URL query parameters). Copying and sharing sidebar content could inadvertently expose private data, so review copied text before sharing.
• Higher Memory Usage: Since there is no limit on the number of captured Referer headers, extensive browsing may increase memory usage, especially on low-RAM systems (<8 GB). Monitor RAM usage and clear the sidebar as needed to optimize performance.
• Temporary Add-On: As a temporary add-on, it requires manual reloading via about:debugging, which ensures no unintended background activity but may interrupt monitoring if not reloaded.
• Browser Interactions: Other extensions (e.g., ad blockers, privacy tools) may modify Referer headers, affecting the add-on’s output. Disable conflicting extensions for accurate monitoring.

Limitations:
The sidebar output may occasionally clear automatically due to browser or extension optimizations. Users should copy important data promptly to avoid loss. Possible reasons include:
• Storage Reset: The background script may reset headers in browser.storage.local due to timeouts or internal limits.
• Browser Memory Management: Firefox may clear DOM content or storage during garbage collection, especially under high memory pressure (e.g., with multiple remote processes).
• Tab Suspension: Firefox’s resource-saving features may reset the sidebar’s state if not persisted robustly.
• WebRequest Listener Issues: Network errors or tab reloads may cause the webRequest listener to reset the headers array.
• Extension Logic: Unintended resets in the background script (e.g., error handling or session management) may clear the sidebar.