The SeaMonkey® Project

The SeaMonkey project is a community effort to develop the SeaMonkey Internet Application Suite (see below). Such a software suite was previously made popular by Netscape and Mozilla, and the SeaMonkey project continues to develop and deliver high-quality updates to this concept. Containing an Internet browser, email & newsgroup client with an included web feed reader, HTML editor, IRC chat and web development tools, SeaMonkey is sure to appeal to advanced users, web developers and corporate users.

Under the hood, SeaMonkey uses much of the same Mozilla Firefox source code which powers such products as Thunderbird. Legal backing is provided by the SeaMonkey Association (SeaMonkey e.V.).

Project News

March 28, 2024

SeaMonkey 2.53.18.2 released

The SeaMonkey project is proud to present SeaMonkey 2.53.18.2: The new release of the all-in-one Internet suite is available for free download now!

2.53.18.2 is a minor bugfix release on the 2.53.x branch and contains a crash fix and a few other fixes to the application from the underlying platform code.

SeaMonkey 2.53.18.2 is available in 23 languages, for Windows, macOS x64 and Linux.

Automatic upgrades from previous 2.53.x versions are enabled for this release, but if you have problems with it please download the full installer from the downloads section and install SeaMonkey 2.53.18.2 manually over the previous version.

For a more complete list of major changes in SeaMonkey 2.53.18.2, see the What's New in SeaMonkey 2.53.18.2 section of the Release Notes, which also contains a list of known issues and answers to frequently asked questions. For a more general overview of the SeaMonkey project (and screen shots!), visit www.seamonkey-project.org.

We encourage users to get involved in discussing and reporting problems as well as further improving the product.

November 14, 2023

SeaMonkey 2.53.18 Beta 1 released

The SeaMonkey project is proud to present SeaMonkey 2.53.18 Beta 1: The new beta test release of the all-in-one Internet suite is available for free download now!

2.53.18 will be an incremental update on the 2.53.x branch and incorporates a number of enhancements, changes and fixes to the application as well as those from the underlying platform code. Support for parsing and processing newer regexp expressions has been added helping with web compatibility on more than a few sites. Crash reporting has been switched over to BugSplat. We also added many fixes and backports for overall platform stability.

Before installing the new version make a full backup of your profile and thoroughly read and follow the Release Notes. We encourage testers to get involved in discussing and reporting problems as well as further improving the product.

SeaMonkey 2.53.18 Beta 1 is available in 23 languages, for Windows, macOS x64 and Linux.

November 6, 2022

SeaMonkey and macOS Ventura

Attention macOS users! The current SeaMonkey release crashes during startup after upgrading to macOS 13 Ventura. Until we have a fix we advise you not to upgrade your macOS installation to Ventura. No usable crash information is generated and this might take a bit longer than usual to fix. This is not a problem with Monterey 12.6.1 or any lower supported macOS version so might even be an Apple bug.

The problem is tracked in Bug 1797696.

The SeaMonkey Internet Application Suite

SeaMonkey has inherited the successful all-in-one concept of the original Netscape Communicator and continues that product line based on the modern, cross-platform architecture provided by the Mozilla project.

• The Internet browser at the core of the SeaMonkey Internet Application Suite uses the same rendering engine and application platform as Mozilla Firefox, with popular features like tabbed browsing, feed detection, popup blocking, smart location bar, find as you type and a lot of other functionality for a smooth web experience.
• SeaMonkey's Mail and Newsgroups client shares lots of code with Thunderbird and features adaptive Junk mail filtering, tags and mail views, web feeds reading, tabbed messaging, multiple accounts, S/MIME, address books with LDAP support and is ready for both private and corporate use.
• Additional components include an easy-to-use HTML Editor, the ChatZilla IRC chat application and web development tools like a DOM Inspector.
• If that's still not enough, SeaMonkey can be extended with numerous Add-Ons that provide additional functionality and customization for a complete Internet experience.