Latest Releases for Legacy Platforms

The SeaMonkey Project only supports the latest stable version of SeaMonkey (see the System Requirements). We do not support any of the applications and versions listed below. If your operating system or computer is no longer supported by official SeaMonkey releases, the only way to continue using officially supported SeaMonkey versions is to upgrade your operating system and/or computer.

Third-Party Projects

There are some legacy platforms that we do not support anymore but for which other projects provide builds that share the same code base as SeaMonkey, Firefox and Thunderbird.

Note: The SeaMonkey Project is not associated in any way with these projects. We cannot provide support or help for these. We cannot verify their security or stability. You should make your own judgement as to the suitability of any of these third party builds you intend to use.

SeaMonkey for OS/2

Dave Yeo provides an SeaMonkey for OS/2 build on his sourceforge projects website.

SeaMonkey for PPC

The SeaMonkey for PPC project provides versions beyond SeaMonkey 2.9 for PowerPC/G4 on Mac OS 10.5.x.


The TenFourFox project provides builds of Firefox for PowerPC (PPC) that are based on Firefox ESR.


The Tenfourbird project provides builds of Thunderbird for PowerPC (PPC) based on TenFourFox.