uBlock Origin is an open-source browser extension that blocks advertisements, trackers, and malware domains. Developed by Raymond Hill (gorhill on GitHub) since 2014. Free, donation-funded, no premium tier. Available for Firefox, Chrome (Manifest V2 version, threatened by Manifest V3 transition), Edge, Safari (limited via Lite version), and most Chromium-based browsers.
What it means in practice
uBlock Origin is the single highest-leverage privacy and performance install you can make. Blocks the third-party tracking infrastructure that defines the modern web (Google Analytics, Facebook Pixel, advertising networks, behavioral data brokers, fingerprinting scripts). Reduces page weight by 30 to 70% on most ad-heavy sites. Reduces page-load time by similar margins. Improves battery life on mobile (less JavaScript to execute). The privacy effect is measurable: a browser with uBlock Origin and the recommended additional filter lists (EasyPrivacy, Peter Lowe’s, Online Malicious URL) loads sites without sending data to dozens of trackers per page that the unprotected browser ships off without user awareness.
Where it shows up
Recommended for: every user, full stop. Differentiated from competitors by the technical model: most “ad blockers” run as pass-through filters that selectively allow ads (AdBlock Plus’s Acceptable Ads program, monetized; AdGuard’s similar arrangement). uBlock Origin has no such program. Operates as content-blocker only, no monetization, no allow-list under commercial pressure. The Chrome Manifest V3 transition is the structural threat: Google’s extension architecture changes limit what content blockers can do, and the uBlock Origin Lite (MV3-compatible) version is significantly less capable than the MV2 version. Firefox is committed to maintaining MV2-equivalent capability for content blockers; this is one of the practical reasons to switch off Chrome.
What you can change today
Install uBlock Origin from the official extension store (Firefox AMO, Chrome Web Store, Edge Add-ons). Open the extension dashboard, Filter Lists, enable EasyPrivacy, Peter Lowe’s Ad and Tracking Server List, and Online Malicious URL Blocklist in addition to the defaults. For high-noise sites, use the element picker (right-click, Block element) to remove specific elements that filter lists do not catch. Donate $5 once via the GitHub sponsor button or the Open Collective; it is the most leveraged privacy donation in the ecosystem.