Web-browser, advanced e-mail, newsgroup and feed client, IRC chat, and HTML editing made simple—all your Internet needs in one application.
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.).
August 26, 2021
SeaMonkey 2.53.9 released
The SeaMonkey project is proud to present SeaMonkey 2.53.9: The new release of the all-in-one Internet suite is available for download now! 2.53.9 is an incremental update from the 2.53.x branch and incorporates a number of changes, including the ability to clear browser history during shutdown and enhancements to the ChatZilla client, and fixes from the underlying platform code. Read the full Release Notes for further information.
If you are upgrading from a 2.49.5 or older release we strongly advise you to make a full backup of your profile before installing the new version.
SeaMonkey 2.53.9 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 2.53.9 manually over the previous
For a more complete list of major changes in SeaMonkey 2.53.9, see the What's New in SeaMonkey 2.53.9 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.
August 11, 2021
SeaMonkey 2.53.9 Beta 1 released
SeaMonkey 2.53.9 Beta 1 is now available for free download on the SeaMonkey website.
2.53.9 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. Before installing it 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 2.53.9 Beta 1 is available in 23 languages, for Windows, macOS x64 and Linux.
August 3, 2021
Automatic updates for 2.53.x releases have been switched on. These will, with a few exceptions, work without any changes for version 2.53.5 and later.
For earlier 2.53.x releases and those releases that cannot be automatically upgraded, including 2.53.5b1, the easiest option is to manually install the latest full version available for download here.
These changes will only work if you have administrator permissions and, on Linux, updates have not been disabled by the distributor.
October 27, 2019
SeaMonkey has a new sponsor!
We are now proudly sponsored by:
A big thanks from the SeaMonkey team! And to all our users and readers don't miss the opportunity to check out the fine products or just buy some great coffee for your pleasure.
September 4, 2019
SeaMonkey and the future
Wow! A new release and two news items together. What is cooking?
With the SeaMonkey 2.49.5 release the 2.49.x line comes to an end. Unless a catastrophic bug is discovered 2.49.5 will be the last ESR 52 based version. Backporting security fixes and at the same time working on the next, already overdue, major release is not possible with the few remaining developers.
Plans are to do further interim 2.53 versions based on a much enhanced Gecko 56 base while working on bringing you the next ESR 60 based 2.57 version. After 2.57 we will decide about the future. The current Mozilla Gecko codebase has seen a flow of constant major changes and api removals in the last 2 years and is no longer really usable for our needs. By the end of the year the SeaMonkey project is expected to be completely independent of Mozilla. We will see how this pans out but we are doing our best and already have a new infrastructure in place where we do builds and website hosting.
We would also like to remind everyone again that this a community project independent of Mozilla. So if you want to continue seeing future SeaMonkey releases please help by either donating money or even better help out with development. We are still committed and hope you are too.
April 3, 2019
Help squashing bugs in mail and news
Our Thunderbird friends ask for help squashing bugs. If you have some spare time help them and also us because SeaMonkey and Thunderbird use a shared codebase for mail and news.
Some Details from the announcement:
We are grateful to have a very active set of users who generate a lot of bug
reports and we are requesting your help in sorting them, an activity called bug
triage. We’re holding “Bug Days” on
No coding or special skills are required, and you don’t need to be an expert or long term user of Thunderbird. Some things you’ll be doing if you participate:
- Help other users by checking their bug reports to see if you can reproduce the behavior of their reported problem.
- Get advice about your own bug report(s).
- Learn the basics about Thunderbird troubleshooting and how to contribute.
But we hope you’ll join us on the 8th or the 13th via #tb-qa on Mozilla’s IRC so that we can put these bugs in their place which helps make Thunderbird even better. If you have any questions feel free to email Ryan.
Visit the Thunderbird Blog to see the full announcement.
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.