Pale Moon (web browser)

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Pale Moon
Pale Moon's computer icon: Artistic impression of Earth's moon tinted blue
Screenshot of Pale Moon version 20.3 running on Windows 8, showing English Wikipedia
Screenshot of Pale Moon version 20.3 running on Windows 8, showing English Wikipedia
Developer(s) M.C. Straver
Initial release October 20, 2009 (2009-10-20)
Stable release 24.7.1 (August 6, 2014; 10 days ago (2014-08-06)[1]) [±]
Development status Active
Written in C/C++
Operating system Windows XP and later, Linux
Engine Gecko
Platform IA-32, x86-64[2]
Available in 85 languages[3]
Type Web browser

Pale Moon is a web browser based on Mozilla Firefox.[5][6] It is available for Windows platforms and distributed by M.C. Straver.[7] Pale Moon builds on Firefox, optimizing for efficiency of code and aimed at current and modern microprocessors.[8] Pale Moon is available free of charge as open source code archive and freeware binary releases.[4] Because it is based on Firefox this makes most of the available Firefox extensions and plugins compatible with Pale Moon.[9]


Based on Mozilla Firefox, Pale Moon provides extra features and modification, such as:

  • Trimming unnecessary components from users' point of view(e.g. silent update service and webrtc )
  • Remaining traditional user-friendly user interface
  • Modern hardware performance boost (with x64 native support) [10]
  • Extra configurability such as scrolling movement and status bar


Pale Moon makes use of compiler optimizations by using Microsoft C compiler's "/O2" and "/Ox" flags, and also by selection of included or excluded features from Mozilla Firefox to increase performance of the browser.[11] The resulting browser will not run on particularly old hardware as a result, but "by cutting out support for older hardware, Pale Moon works with an optimized code base that takes full advantage of modern processor instruction sets."[12]

Further performance tuning is achieved by removing uncommonly used functions of Firefox, including accessibility features, parental controls, crash reporter, ActiveX and Active Scripting.[7][13]

Additionally, Pale Moon has included pdf.js that is included in Firefox, but it is disabled by default.[14]

These optimization techniques increased the subjective performance of Pale Moon as compared to Firefox.[5][7][15][16]

User interface[edit]

The user interface of Pale Moon since version 4.0 substantially differs from that of Firefox. The status bar was re-added by the authors to keep the information, provided by web applications and the messages about the current state of the browser accessible yet less intrusive, as well as keeping other status elements that were removed from the Firefox user interface (page load progress indicator, file download indicator) by bundling an edited version of an open source status bar extension until version 12, after which that extension was fully integrated into the core of the browser.[17][18] The tab bar in Pale Moon is also preserved below the other toolbars in the application (as opposed to Firefox's and Google Chrome design). The developer also reordered UI controls with a goal to collect the control elements in the same place to improve the user experience from the usability point of view.[19]

Incompatibility with older hardware[edit]

Since Version 3.x of the browser (based on Firefox 3.x source code) is maintained separately to provide support for older processors that don't support the SSE2 instruction set, which is required to run Pale Moon versions 4.0 and later.[20] In August 2012, the head developer announced the end-of-life for that legacy Pale Moon browser citing dropped functionality, maturation of the next-generation code and increasing difficulty for back-port security patches (especially issues related to JavaScript).[21]


The browser used to follow Mozilla Firefox's rapid release schedule before 12.0 was released. Subsequent versions are released sticking to the ESR versions of Firefox with additional and independent development on top.[22]

Relationship with Firefox[edit]

The user interface of Pale Moon is basically the same as what was the Firefox interface before about version 18. For instance it retains full customisability of the toolbars, and option to have no tab bar showing. Developers of Pale Moon mainly oppose to the current movement of the development of firefox especially for its new user interface—Australis.[23] Pale Moon has recently begun to come to some prominence due to the number of long-standing Firefox users objecting to the unwanted changes of Firefox 29 onwards.


Like Firefox, Pale Moon is released open source, with the source code residing under the Mozilla Public License 2.0 except for parts relating to branding. Unlike Firefox, however, the Pale Moon binaries may only be redistributed under certain conditions.[4] According to the author, this is to prevent the possibility of any confusion with tainted versions. The project's name, logo, and other artwork are the intellectual property of M.C. Straver, and cannot be used in other third party Firefox builds or other related products without the author's prior permission.[13]

See also[edit]


  1. ^ Pale Moon Release Notes
  2. ^ Minimum system Requirements at Home Page
  3. ^ "Pale Moon language packs". Moonchild Productions. Retrieved 16 June 2012. 
  4. ^ a b c "Pale Moon redistribution", Official website, retrieved 2012-02-16 
  5. ^ a b Purdy, Kevin (2010-04-14), "Pale Moon Is a Faster Firefox Clone for Windows and Linux", Lifehacker, retrieved 2012-02-16 
  6. ^ "Pale Moon 24.6.2" by Razvan Mihai Asmanow Serea, Neowin, 16 June 2014
  7. ^ a b c Snyder, Bill (2012-01-10), "Pale Moon: The Fastest Browser You've Never Heard Of", Consumer Tech Radar (CIO Blogs), retrieved 2012-02-16 
  8. ^ Firefox Optimized for Windows – Pale Moon Custom Built Browser, TECK.IN, 2011-04-08, retrieved 2012-02-16 
  9. ^ Why do some add-ons not work (properly) with Pale Moon?. "Pale Moon: Frequently Asked Questions (F.A.Q.)". Moonchild Productions. Retrieved 30 July 2014. 
  10. ^ Pale Moon x64 build
  11. ^ "Pale Moon Home Page", Pale Moon Home Page (Moonchild Productions), retrieved 2013-04-01 
  12. ^ Wilson, Mark (2011-04-06), "Pale Moon 4: Firefox's leaner, meaner twin – and, whoa is it fast", betanews, retrieved 2012-02-16 
  13. ^ a b "Pale Moon: Technical Details", Official website, retrieved 2012-02-16 [non-primary source needed]
  14. ^ "Pale Moon: Technical Details". Retrieved 1 May 2014. 
  15. ^ Williams, Mike (2011-06-25), "Pale Moon 5 outshines sibling Firefox 5", betanews, retrieved 2012-02-16 
  16. ^ Noyes, Katherine (2011-08-27), "Want a faster Firefox? Pale Moon can help", PC World, retrieved 2012-02-16 
  17. ^ Finalization of the integration of status bar (Part of PM12 official announce in forums)
  18. ^ Pale Moon – Release Notes, retrieved 2012-06-01 
  19. ^ "About the Pale Moon layout in version 4 and later", Official website, retrieved 2012-02-16 [non-primary source needed]
  20. ^ "Pale Moon: AthlonXP", Official website, retrieved 2012-02-23 [non-primary source needed]
  21. ^ End-of-Life announcement for Pale Moon "Legacy" (Official forum)
  22. ^ Pale Moon version numbers (change of plan) – Pale Moon forum (Official post from main developer)
  23. ^ Palemoon FAQ

External links[edit]