NetShield

NetShield is a comprehensive content blocking extension for Firefox that uses an efficient filtering engine with hundreds of thousands of built-in rules loaded from local files to block advertisements, tracking scripts, malware domains, social media widgets, and annoying page elements across all websites without sending any browsing data to external servers or third parties. The extension intercepts web requests through the webRequest API and matches URLs, domains, and resource types against pattern-based filter rules to determine whether each request should be blocked, redirected to an empty resource, or allowed through, with support for exceptions, domain-specific rules, content type filtering, and cosmetic element hiding injected directly into pages via content scripts.

NetShield categorizes blocked content into five categories: ads, trackers, malware, social, and other, each with extensive pattern lists, and provides category-based toggles in the settings page so you can individually enable or disable blocking for each category. The settings page also includes an enhanced stealth mode that obfuscates browser fingerprinting vectors by hiding plugins and MIME types, disabling WebRTC, and breaking the Battery Status API, along with a blocking analytics toggle to control whether statistics are recorded.

The popup displays real-time blocking statistics including total blocked requests, today's count, blocked items on the current page, and the number of active filter rules, along with a category breakdown with visual bars, a live line graph showing blocking activity over the last 30 minutes, a list of the most blocked domains, and a detailed event log showing every blocked request with its type, URL, domain, and timestamp. From the popup you can also toggle blocking on and off, upload custom filter rules in standard Adblock Plus format, clear custom rules, navigate to the dashboard, open settings, and export block data as JSON.

The homepage dashboard provides a full overview with total blocked, blocked today, active rules count, and safelisted domains counters, along with category distribution bars, a top blocked domains list, and quick links to settings, data export, and support. The extension also strips tracking parameters from URLs including utm_*, fbclid, gclid, and dozens more, removes identifying request headers like x-forwarded-for and x-real-ip on tracked domains, and reduces referrer information sent to third parties.

When a blocked domain is detected, NetShield displays a warning page showing the blocked domain and the reason for blocking, with a thirty-minute bypass button for non-malware domains and a return button for going back to the previous page, while verified malware domains show a critical threat warning with bypass disabled entirely. A safelist system allows certain domains to bypass blocking, and per-domain bypasses are remembered for thirty minutes. The extension also supports fetching external filter lists from AdGuard and EasyList sources daily to supplement the built-in rules, stores blocking statistics and event history using the storage API, and supports full data reset from the settings page.