Basilisk

Basilisk Development Team·Basilisk.Basilisk

A XUL-based web-browser built on top of the Unified XUL Platform (UXP). This browser is a close twin to pre-Servo Firefox in how it operates.

Basilisk is a free and Open Source XUL-based web browser, featuring the well-known Firefox-style interface and operation. 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.

winget install --id Basilisk.Basilisk --exact --source winget

Latest 52.9.2026.06.12·June 14, 2026

Release Notes

UXP Changes:

  • Fixed a webaudio channel mixing regression resulting in broken audio.
  • Added powerPreference to canvas WebGL context for web compatibility.
  • Implemented support for the lch color space in CSS.
  • Added a base implementation for CSS stylesheet constructors.
  • Added a base implementation for CSS aspect-ratio sizing.
  • Added support for CSS min(), max() and clamp() functions.
  • Added support for CSS logical border radius properties.
  • Added support for ranges in CSS media queries.
  • Added support for CSS shadow parts.
  • Added support for degenerate CSS values infinity, -infinity and NaN.
  • Implemented full LoongArch64 Baseline/Ion/WASM JIT compiler support.
  • Added AV1 decoding with Dav1d for more performant AV1 video. Note: AV1 is now enabled by default on non-x86 Basilisk builds.
  • Added ES2024 Arraybuffer transfer APIs (resize, transfer, transferToFixedLength, detached, maxByteLength and resizable).
  • Added support for growable/resizable SharedArrayBuffers and DataViews.
  • Added ES2024 grouping builtins (map .groupBy).
  • Added ES2024 resolver builtins (.withResolvers()).
  • Added ES2024 String well-formed functions (.isWellFormed() and .toWellFormed()).
  • Added support for symbols as weak collection keys.
  • Added support for Atomics.waitAsync.
  • Added support for FinalizationRegistry (part of the WeakRef spec).
  • Switched our build system to Python 3. See implementation notes.
  • Linux: removed dbus-glib dependency.
  • Linux: Added EGL as a preferred OpenGL provider with GLX fallback; GLX remains the configured default as there are still some unresolved issues with EGL.
  • Improved JS performance by porting across various enhancements from Mozilla.
  • Fixed various application crashes.
  • Further improved compatibility with building for Loongson architectures.
  • Further improved hardware accelerated decoding of WMF videos.
  • Fixed ARM assembler issues in the Goanna back-end.
  • Improved parallel JS parsing tasks.
  • Improved CSS handling of calc() for web compatibility, allowing it in many more places (e.g. color() and z-index). For compatibility and performance reasons, we still strongly recommend that you use CSS variables to make calculations where possible.
  • Ported several smaller performance improvements from the Dactyloidae project.
  • Aligned CSS border width calculations with mainstream, for web compatibility. Please note that this may impact some themes that might rely on fractional border rounding (instead of truncation).
  • Removed the CloudFlare workaround as it should no longer be necessary with general image size handling improvements. The preference will no longer do anything.
  • White-listed driver vendors for VMWare, VirtualBox, VirtIO and Parallels to allow hardware accelleration as much as possible in VM environments.
  • Changed the implementation of WeakRef support to be always enabled in its full implementation (this was already enabled in Basilisk by default).
  • Fixed some build issues on NetBSD.
  • Mac: Fixed a pertinent crash due to font handling on OS X 10.7 through 10.11.
  • Mac: Fixed build compatibility with 32-bit MacOS and Mac on PowerPC hardware.
  • Fixed a devtools crash on Big Endian machines.
  • Fixed an issue causing rendering artifacts on excessively large border-radius values (e.g. Tailwind CSS).
  • Fixed a stack corruption issue in nsLocaleService that could lead to crashes.
  • Implemented some ANGLE upstream fixes.
  • Fixed a regression that would cause crashes to desktop when using certain extensions or visiting certain websites.
  • Updated NSS to 3.90.11 (UXP), picking up a number of upstream security fixes.
  • Fixed potential security issues with audio channel mixing, MP3 decoding (DiD), international text display, DOM workers (DiD), reading of files (DiD), and the ANGLE graphics library.
  • Another large security audit was performed of 190 security-sensitive reported bugs. Many security issues were addressed, including potential crash scenarios and code correctness issues. As a summary: 18 potential vulnerabilities were found applicable and fixed, another 18 issues had DiD code changes applied, and 4 were already mitigated by us before being reported. Of the reported security bugs, 150 were not applicable to our code (with a good portion once again pertaining to e10s/multi-process browser architectures).

Basilisk Changes:

  • Fix an issue when searching with CTRL/CMD+F in PDF files opened in PDF.js.
  • Enable dom.serviceWorkers.enabled pref by default
  • Fix a bug where if Basilisk is set to not remember history and is set as the default PDF app for the OS, it will loop and open a bunch of tabs over and over when trying to open a PDF file in PDF.js.
  • Remove leftovers from Firefox's "remote troubleshooting" functionality as it is not used by Basilisk.
  • Remove FinalizationRegistry polyfill as UXP natively supports this function now.
  • Port all Basilisk Python files to Python 3.
  • Built on UXP commit: 83826f1f34

Included Polyfills:

  • This release includes the following polyfills:
    • image.decode
    • Intl.DisplayNames
    • Intl.Segmenter
    • en-US only Intl.ListFormat
    • Microsoft-specific (Outlook, Azure, etc) webauthn shim
    • TestDecoderStream
    • TextEncoderStream
    • TransformStream
    • ReadableStream pipeTo
    • ReadableStream pipeThrough
    • getAnimations
    • elementFromPoint finite values

UXP Implementation Notes:

  • The Dav1d AV1 video library was added to UXP, which allows for greatly better performance in AV1 video playback, especially at higher resolutions. The codec is still very computationally intensive, so this does rely pretty heavily on having modern, capable hardware. As an additional note, this library requires AVX hardware to properly decode at speed. Due to the fact that Basilisk targets pre-AVX hardware, all x86 and x86_64 builds are configured to still use libaom. If you build from source, there is a new configure option --enable-libaom to build with the reference library instead of Dav1d.
  • If you build from source yourself, you will no longer have to rely on a distribution that offers Python 2.7. Please note there is some variance in Python 3 versions and not every version will work due to feature changes within the Python 3 range. Versions 3.4 through 3.14 should work; YMMV on other versions. Please ask for help on the forum if you can't figure it out.

Installer type: nullsoft

ArchitectureScopeDownloadSHA256
x86DownloadCA982BF03E159782AFEA6B45A7F859C6963C19F773DEEDB8970F874150A43C65
x64Download523380CAF5FABE169A541AFCF55A1DD4567DBCBF5AE53AE9D33599F5CC496F05

Details

Homepage
https://www.basilisk-browser.org/download.html
License
MPL-2.0
Publisher
Basilisk Development Team
Support
https://www.basilisk-browser.org/contact.html
Privacy Policy
https://www.basilisk-browser.org/privacy.html
Copyright
Copyright ©2022-Present The Basilisk Development Team. All rights reserved.

Tags

browserinternetwebweb-browserwebpagexul

Older versions (8)

52.9.2026.04.15
ArchitectureScopeDownloadSHA256
x86Download03BBF685AE43A808D6DA97C222C1D1981709655237ADEFF49898F91AAEC758E2
x64Download3F3E0D1E75FE812B02BA463911AA7C261A6CB3C4F2EEDB08023508F7D116E5CB
52.9.2026.03.09
ArchitectureScopeDownloadSHA256
x86DownloadBABF9B376B75124D935BEA8F1001714DE1546832AD19BF560BD7500F89A2B10E
x64DownloadBA8AD91128D28FD438F3DF51A201608CAE9A250B2CC6D9B7E637DD6B9830D3BE
52.9.2026.01.23
ArchitectureScopeDownloadSHA256
x86Download2BD0EB23D1F3926CA33298FD1297ECEC948E0EC500FEBFCB0EFF93BB0AF35520
x64DownloadD2E7454DEDC4C03649AF201BD37A8CC6622E516400B6A00EE208E5436654AB95
52.9.2025.10.10
ArchitectureScopeDownloadSHA256
x86DownloadDA1493CD66A36BD57843BF2BCD2DBE8F0A1CD5F96AF2B5A1465C0A2B4989CB90
x64DownloadE06729D01F22E710120CA9321B13884BA5823E5BB4F417BE1647847F068043EF
52.9.2025.07.04
ArchitectureScopeDownloadSHA256
x86Download95B9615C78DC626729353768ECBDD684DC9B1DFE9DB15FA36D296C8A1455ECA9
x64Download0BE9F04F23063FAC86239D1F436E4BC9822710FB7F9B397F76B9AFE5B51AF245
52.9.2025.06.13
ArchitectureScopeDownloadSHA256
x86Download0C9C868E546EF7D6553452492A75EEDA00AD9D8AED20197051963E0E80EFE15F
x64DownloadA4D5F1DA0DDB4B038706B654FD126D32E8DD760F4BFB619C0006FE5B433DE6F5
52.9.2025.04.23
ArchitectureScopeDownloadSHA256
x86DownloadB1C8B770D767FB21F3B320E6C98494D6219764468D3E7B2A419EFBD701E1D82D
x64DownloadAEA84DC5CCA8D16388BE7E8D2A2B97D50C7C106AD3457D227F8657EA2FEC7A29
52.9.2025.02.22
ArchitectureScopeDownloadSHA256
x86Download757A542ED6969AD0E92BA4782A95B4EEF364A7A37B1AF92B8D1079FF5C130D6C
x64Download1A2066A4508D1C4AF417FE2DD3CBE55FE2F8D481BC3EB4617C7147416C3BCA27