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Basilisk 2019.06.08


Basilisk is a free and Open Source XUL-based web browser created by the developers of the Pale Moon browser. It is based on the Goanna layout and rendering engine (a fork of Gecko) and builds on the Unified XUL Platform (UXP), which in turn is a fork of the Mozilla code base without Servo or Rust.

Basilisk as an application is primarily a vessel for development of the XUL platform it builds upon, and additionally a potential replacement for Firefox to retain the use of Firefox Extensions. It aims to retain useful technologies that its sibling Firefox has removed.

Requires Windows 7 or later. Windows XP or Windows Vista are not supported.

Main features:

  • Full support for JavaScript's ECMAscript 6 standard for modern web browsing.
  • Support for all NPAPI plugins (Unity, Silverlight, Flash, Java, authentication plugins, etc.).
  • Support for XUL/Overlay Mozilla-style extensions.
  • Experimental support for WebExtensions (in gecko-target mode). Please note that some Mozilla-specific WebExtension APIs are not yet available.
  • Support for ALSA on Linux.
  • Support for WebAssembly (WASM).
  • Support for advanced Graphite font shaping features.
  • Support for modern web cryptography: up to TLS 1.3, modern ciphers, HSTS, etc.

Important differences with Mozilla Firefox:

  • Uses Goanna as a layout and rendering engine. Goanna behaves slightly differently than Gecko in certain respects and may result in different display of web pages. e.g.: Goanna renders gradients in a more accurate color space (non-premultiplied).
  • Builds on UXP, our XUL platform in development. As such XUL is alive and well in this browser and will not be deprecated.
  • Has some long-standing known issues with the Mozilla code-base fixed (e.g. CVE-2009-1232).
  • Does not use Rust or the Photon user interface. You can expect a familiar interface as-carried by Firefox between v29 and v56.
  • Does not use Electrolysis (e10s, multi-process browsing).
  • Does not require walled-garden extension signing.

Basilisk 2019.06.08 release notes:

This is a development, bugfix and security release. Please note that Google Widevine DRM might currently not work in new installations due to Google's licensing model.


  • Removed unused code: contextual identity, crash reporter leftovers, SecurityUI telemetry, "enhanced" new tab tiles.
  • Updated the installer and internal updater.
  • Removed all Firefox Accounts code and replaced the Sync client for compatibility.
  • Implemented JavaScript parser improvements and the TC39 toString() revision proposal for web compatibility.
  • Improved handling of url() tokens in CSS to better handle incorrect syntax.
  • Updated the embedded emoji font for broader emoji coverage.
  • Fixed print failure for some web pages.
  • Fixed Linux XRender performance issues over remote connections (e.g. X2Go).
  • Improved JavaScript engine performance: dead compartment collection,
  • Fixed an address bar focus issue in Private Browsing mode.
  • Improved rendering performance for certain websites (with complex event regions).
  • Implemented several ECMAScript 2019 features (String trimStart/trimEnd, Array flat/flatMap, Symbol description)
  • Fixed security issues: CVE-2019-7317, CVE-2019-11701, CVE-2019-11698, CVE-2019-9817 (DiD), CVE-2019-11700, CVE-2019-11696 and CVE-2019-11693.
  • Fixed several memory safety hazards and crashes.

Download: Basilisk 2019.06.08 (32-bit) | Portable | ~50.0 MB (Open Source)
Download: Basilisk 2019.06.08 (64-bit) | Portable
View: Basilisk Website

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