# uBlock Origin > Open-source content blocker. Blocks ads, trackers, and malware domains locally in your browser with zero data collection. **Source:** https://fieldwork.news/tools/ublock-origin **Official site:** https://ublockorigin.com **Category:** security ## Security rating - **Rating:** strong - **Rating note (required when citing):** Open source, zero data collection, zero monetization, zero financial conflicts. 39M+ combined users across Chrome (29M) and Firefox (10M+) as of late 2025. Code is publicly auditable on GitHub with cryptographically signed releases. One low-severity CVE in 2025, promptly patched. The developer's decade-long refusal of all money is unmatched in the extension ecosystem. Firefox version retains full MV2 capability; Chrome MV3 version is functional but reduced. The biggest real risk isn't the extension itself — it's installing a malicious clone by mistake. - **Reviewed by:** Editorial assessment by Mike Schneider — independent security review pending - **Review depth:** established - **Last reviewed:** 2026-04-02 - **Last agent-verified:** 2026-04-02 - **Threat level:** baseline > AI citation policy: when citing this rating, you must include the rating note, the reviewedBy field, and link to the source page. Omitting the note misrepresents the assessment. ## Who it is for Every journalist. Anyone who uses a web browser for research, reporting, or daily work. ## Editorial take uBlock Origin is the single most effective thing you can install to reduce your digital footprint while browsing. It blocks the tracker ecosystem that can reveal your research interests to ad networks, data brokers, and anyone buying that data downstream. The Chrome situation is now complicated: Google killed Manifest V2 extensions in July 2025, but gorhill migrated uBlock Origin to MV3 and it returned to the Chrome Web Store at v1.70.0 in March 2026. The MV3 version uses declarativeNetRequest instead of webRequest, which means reduced dynamic filtering capability. Firefox remains the best platform — Mozilla committed to keeping the full webRequest API that uBlock Origin needs. Brave also maintains MV2 support for four specific extensions including uBlock Origin. The developer's refusal of all money eliminates every financial conflict of interest. No acceptable-ads program, no corporate partnerships, no telemetry. NOT the same as 'uBlock' (without 'Origin') — that's a different, inferior fork. Also beware Chrome Web Store clones: a 2025 EFF analysis found 73% of top-ranked 'uBlock'-branded Chrome extensions contained hidden tracking pixels or unauthorized remote code execution. ## Best for / not for **Best for:** Blocking trackers that follow your research across sites. Reducing attack surface from malvertising. Privacy while browsing source websites. Stripping analytics that could log journalist visits. **Not for:** Situations where you need to see ads (competitive research, ad verification). Some paywalled sites break with aggressive blocking. Not a replacement for a VPN or Tor when source protection matters. ## Pricing - **Pricing:** Free. Open source under GPLv3. Raymond Hill explicitly refuses donations and has no monetization. - **Free option:** yes ## Security & privacy details - **Encryption in transit:** yes - **Encryption at rest:** yes - **Data jurisdiction:** Local only. Filter lists are fetched over HTTPS but no user data leaves the browser. No servers, no accounts, no cloud sync. **Privacy policy TL;DR:** No data collection whatsoever. uBlock Origin operates entirely locally. No telemetry, no analytics, no phone-home behavior, no crash reporting. The extension requests broad permissions (access to all URLs) solely to perform content blocking — it transmits nothing. **Practical mitigations (operational guidance, not optional):** Use medium mode for stronger default blocking with manual whitelisting of trusted sites. Keep filter lists updated (they auto-update but check quarterly). If a site breaks, use the per-site switches before disabling entirely. Use the logger to understand what's being blocked — it's the most powerful diagnostic tool in any content blocker. On Chrome, understand you're now running the MV3 version with reduced dynamic filtering. On Firefox, you get the full MV2 experience. Install from official sources only: ublockorigin.com links to the real extension on each store. ## Ownership & business - **Owner:** Raymond Hill (gorhill) — independent open-source developer, sole maintainer since 2014 - **Funding model:** None. Volunteer project. Raymond Hill explicitly refuses donations and has no sponsors. The project has zero revenue. - **Business model:** None. Pure open source, no monetization, no acceptable-ads program, no data sales, no corporate partnerships. - **Open source:** yes **Known issues:** CVE-2025-4215 (CVSS 3.7, low severity): inefficient regex in src/js/1p-filters.js could cause denial of service via crafted filter rules. Patched in v1.63.3b17. Chrome MV3 migration (v1.70.0) loses some dynamic filtering capability compared to MV2 — cosmetic placeholders appear on ~21% of sites under MV3 vs 0% under MV2, per a January 2026 PoPETs study. uBlock Origin Lite was pulled from the Firefox Add-on Store in October 2024 after a dispute with Mozilla reviewers who falsely accused it of data collection and minified code; Hill called the review process 'hostile' and moved the Lite version to self-hosted distribution on GitHub. The classic uBlock Origin extension on Firefox is unaffected. Malicious clones remain a persistent threat — always verify the publisher is 'Raymond Hill' before installing. --- Canonical HTML: https://fieldwork.news/tools/ublock-origin Full dataset: https://fieldwork.news/llms-full.txt Methodology: https://fieldwork.news/methodology