|Initial release||November 8, 2010|
|FPR32.4 (September 6, 2021)|
|FPR32b1 (April 2, 2021)|
|Operating system||Mac OS X 10.4 and 10.5|
|License||Mozilla Public License, GNU General Public License, others|
In 2010, Mozilla's Mike Beltzner announced that the forthcoming Firefox 4 would not be released for Power Macintosh computers, compatibility with Mac OS X Tiger having already been removed, making Firefox 3.6 the last supported release of Firefox on the older architecture and platform. Mozilla stopped making PowerPC-compatible universal builds of Firefox 4 with beta 7.
After Mozilla announced the extended support release (ESR) of Firefox, Cameron Kaiser stated that starting with version 10 of TenFourFox, stable releases of TenFourFox will be based on Firefox ESR to reduce maintenance burden. Between major ESR versions, developers tracked changes in Firefox's 6-week rapid release cycle with test builds only to determine whether or not they would still be able to build the software after the next ESR version was released. Only minor ESR updates were advertised as suitable for general consumption.
In December 2015, Kaiser declared TenFourFox would move away directly from Firefox source code with 45 ESR, citing an inability to port later versions due to operating system and Rust compiler limitations. The first of the "Feature Parity Releases," or FPRs, in which major later Firefox features were backported to TenFourFox's modified Firefox ESR 45 base, was released after the official end of Firefox ESR 45 support on June 13, 2017. The TenFourFox FPR series of releases include additional later features as well as backported security patches from the most current supported Firefox ESR.
On March 29, 2021, Kaiser announced that further development of TenFourFox would wind down over the next several months, largely due to his time becoming very limited and the increasing amount of development work that was required to keep TenFourFox up-to-date. The last official feature parity release, version FPR32, was released on April 19, 2021. The first security parity release, version FPR32.1 (a.k.a. FPR32 SPR1), was released on May 28, 2021. He has stated that he will guarantee security and stability patches through the end of Mozilla support for Firefox 78ESR, scheduled for October 5, 2021.
Due to its compatibility with the older operating system, the browser lacks some of the features of current Firefox versions. In particular, it does not fully support Core Text, so it does not understand Apple Advanced Typography features in certain international fonts; it does not support graphics acceleration for compositing; and it does not support WebGL (because PowerPC Tiger does not support OpenGL 2). Furthermore, for security and maintainability reasons, NPAPI plugins support was deprecated, and has been subsequently removed.