Web-browser, advanced e-mail, newsgroup and feed client, IRC chat, and HTML editing made simple—all your Internet needs in one application.
Download NowSeaMonkey 2.53.15
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.).
February 28, 2023
SeaMonkey 2.53.16 Beta 1 released
SeaMonkey 2.53.16 Beta 1 is now available for free download on the SeaMonkey website.
2.53.16 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. There is now support for webextension dictionaries and language packs and there is a new shared styling for trees. Some minor updates to web compatibility. Support for macOS 10.9 to 10.11 has been restored. 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 2.53.16 Beta 1 is available in 23 languages, for Windows, macOS x64 and Linux.
January 20, 2023
SeaMonkey 2.53.15 released
The SeaMonkey project is proud to present SeaMonkey 2.53.15: The new release of the all-in-one Internet suite is available for download now! 2.53.15 is an incremental update from the 2.53.x branch and incorporates a number of changes as well as fixes from the underlying platform code.
The SSL handling code (NSS) has been updated to Mozilla ESR102 level. The release also contains some minor updates for web compatibility like implementing microtasks. Improvements for filtering / tagging mails have been put in. Some changes have been made to the preferences and locale code handling so please test the add-ons that you have installed. This update also includes fixes for switching to fullscreen and for the crashes during startup on macOS 13 Ventura.
Before installing the new version we strongly advise that you 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 to further improve the product.
SeaMonkey 2.53.15 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 upgrading or you need to upgrade from
a version earlier than 2.53.5, please download the full installer from the
downloads section and install SeaMonkey 2.53.15 manually over the previous
For a more complete list of major changes in SeaMonkey 2.53.15, see the What's New in SeaMonkey 2.53.15 section of the Release Notes, which also contain 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 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.