The new major release of the all-in-one Internet suite is available for download now. Building on the same Mozilla platform as the newest Firefox release, it delivers the latest developments in web technologies such as HTML5, hardware acceleration and improved JavaScript speed.

f you are using macOS 15.1.x please update to 15.2. Because of a bug in the OS SeaMonkey can not be started via Finder or Dock without workarounds. This applies to older versions too.

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

Features

Browser

  • Tabbed browsing gives you a better way to surf the net. You no longer have to open one page at a time. With tabbed browsing, open several pages at once with one click. Plus, your homepage can be multiple pages, in tabs. And if you mistakenly close a tab or window, functionality to Undo Closed Tab or Window helps you bring it back to continue working with it.
  • Session restore brings back all your open windows and tabs after the rare occasion that SeaMonkey crashes – and if you wish even when you close and reopen the browser or restart your computer. However, crashes should be rare nowadays because crashing plug-ins will no longer take the whole application down.
  • SeaMonkey's powerful Add-ons Management provides almost infinite possibilities to extend your Internet experience both through installing additional functionality created by others and even freely developing your own extensions and providing them to the rest of the SeaMonkey community.
  • SeaMonkey's unique Data Manager serves as a central management interface for all kinds of site-specific data, including cookies, permissions (e.g. image blocking), preferences, passwords and form data.
  • Lightweight themes (Personas) let you give your SeaMonkey a personal touch through simple theming. You can choose from thousands of Themes!
  • Feed detection notifies you when web pages offer RSS or Atom feeds, and feed preview lets you view their contents and choose a reader with which to subscribe to those – including an internal reader in the Mail & Newsgroups component of SeaMonkey.
  • Smart Location Bar enables you to search your visited web pages as you type into the browser's location bar and find what you want to re-visit as quickly as possible by learning which pages you visit frequently.
  • Popup blocker lets you surf the web without interruption from annoying ads.
  • Find as you type gives you another way to navigate a page. Just start typing to jump from link to link or to find a word or phrase within a page.
  • Safe Mode can help you solve problems that might occur, e.g. with incompatible add-ons. If you need to ask someone for support, the Troubleshooting Information page provides quick access to basic technical information.
  • Plus all the features a modern browser should have, including: Advanced security settings, download management, web form autocompletion, themes, toolbar customization, multi-language and multi-platform support, plus support for the latest web standards.

Mail & Newsgroups

  • Tabbed Mail lets you manage your mail and folders in parallel, without losing control of where you're at when reading, replying to and working with messages in more complex patterns.
  • Junk mail controls help you take back control of your e-mail from spammers. SeaMonkey's adaptive junk mail control gets smarter with use and is personalized to the e-mail that you receive.
  • Manage your mail with customizable Tags and Mail Views. Color code your e-mail to help you prioritize. Filter your mail with views to help you sort through your e-mail much faster.
  • Multiple accounts support helps you manage all your mail through one interface.
  • Blogs & News Feeds is a reader for RSS and Atom feeds right in your messaging center that eases your reading of information from all across the web.
  • SeaMonkey Mail & Newsgroups includes enterprise-ready features such as S/MIME, return receipts, address books, LDAP support, and digital signing.

Composer

  • SeaMonkey's powerful yet simple HTML editor keeps getting better with dynamic image and table resizing, quick insert and delete of table cells, improved CSS support, and support for positioned layers. For all your documents and website projects, Composer is all you need.

IRC Chat ("ChatZilla")

  • Chat on IRC networks with this simple yet powerful IRC client. Multiple networks and channels are easy to keep track of in a familiar tabbed interface.
  • You can change the look and feel of the chat with motifs; choose from several built-in motifs, many more downloadable, or create your own with CSS.

Web Development Tools

  • DOM Inspector enables you to dig into the document structure of web pages, add-ons or even the SeaMonkey "chrome" itself and inspect a huge number of properties of any element in that structure, including JavaScript objects and CSS styles.
  • JavaScript Debugger ("Venkman") lets you debug JavaScript code on your websites, add-ons and even in SeaMonkey itself with a suite of powerful debugging tools.

What's New

The SeaMonkey project is proud to present SeaMonkey 2.53.22:

  • 2.53.22 is 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. We have also added many fixes and backports for overall platform stability.
  • Please be advised that 2.53.21 was the last release with 32-bit versions for Windows and Linux, this version is only 64-bit.
  • If you are using macOS 15.1.x please update to 15.2. Because of a bug in the OS SeaMonkey can not be started via Finder or Dock without workarounds. This applies to older versions too.

We are aware of numerous websites breaking because of only supporting the latest Chrome or Firefox versions. We are trying to address this and progress has been made in a different source code branch but the code is not ready for general distribution yet.