The SeaMonkey project is a community effort to develop the SeaMonkey all-in-one internet application suite. 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 source code which powers such successful siblings as Firefox, Thunderbird, Camino, Sunbird and Miro. Legal backing is provided by the Mozilla Foundation.
SeaMonkey 2.53.5 release notes:
This version makes changes to your profile that can"t be reverted in case you want to go back to a previous version of SeaMonkey. You MUST absolutely do a full backup of your profile before trying SeaMonkey 2.53.5. Automatic upgrades from previous versions are disabled for this release. Please download the full installer from the downloads section and install SeaMonkey 2.53.5 manually over the previous version.
What"s new:
- Provide WebP support bug 1653869.
- Add startpage.com as a search engine available to all locales bug 1655283.
- Added av1 support.
- Included latest version of freetype2.
- Added support for the resizeObserver web API.
- Support for rust 1.47.0 on Linux and macOS platforms.
- Dropped support for use of system sqlite.
- Various security and general platform fixes.
SeaMonkey 2.53.5 contains (among other changes) the following major changes relative to SeaMonkey 2.49.5:
- The Bookmarks Manager has switched its name to Library, and now also includes the History list. When invoking History, the Library will be shown with the History list selected. The extensive modifications were needed because of Mozilla Gecko platform API changes.
- Download Manager has been migrated to a new API. Although it looks pretty much the same as before, the search option is missing and some other minor details work differently. The previous downloads history is removed during the upgrade.
- The layout panel was added to the CSS Grid tools.
- TLS 1.3 is the default SSL version now.
- The only NPAPI plugin which will work with SeaMonkey 2.53.5 is Flash. Support for other NPAPI plugins like Java and Silverlight has been removed. For displaying pdf files in the browser you can use pdf.js-seamonkey from Isaac Schemm.
- SeaMonkey now uses a new api for formatting regional data like time and date. Default is to use the application locale of the current SeaMonkey build. If you use a language pack or a different OS formatting this is usually not desired. You can change the formatting from the application locale to the regional settings locale (OS) in the preferences dialog under "Appearance".
- SeaMonkey 2.53.5 uses the same backend as Firefox and contains the relevant Firefox 60.8 security fixes.
- SeaMonkey 2.53.5 shares most parts of the mail and news code with Thunderbird. Please read the Thunderbird 60.0 release notes for specific changes and security fixes in this release.
- Additional important security fixes up to Current Firefox 78.4 ESR and a few enhancements have been backported. We will continue to enhance SeaMonkey security in subsequent 2.53.x beta and release versions as fast as we are able to.
SeaMonkey-specific changes
- SeaMonkey now uses gtk3 on Linux. If you experience a problem because of this please file a bug and link it to bug 1367257. Please try another OS theme first. Some of them are buggy and cause problems with SeaMonkey, Thunderbird and Firefox.
Download: SeaMonkey 32-bit | SeaMonkey 64-bit ~40.0 MB (Freeware)
View: SeaMonkey Website