Otter Browser vs SeaMonkey (2026): which should you pick?
As of Nov 13, 2026, Otter Browser and SeaMonkey share a 3.0 GPA, both are free, so the choice depends on which platforms you need.
Checked Nov 13, 2026 · graded Nov 13, 2026 by ToolGPA
They get the same grade on all five counts.
Price, platforms and features side by side. The table says where each price was read and when.
Otter Browser
Open-source Qt browser that revives the classic Opera 12 interface
SeaMonkey
All-in-one internet suite with browser, mail, chat and HTML editor
Which one is for you
Pick Otter Browser if
- Fits if you miss the classic Opera 12 layout
- Makes sense if you want a light, tweakable desktop browser
Look elsewhere if
- Skip it if you use a Mac or a phone, as macOS is not named
- Not for you if you want quick fixes: recent weekly reports show about seven commits by one author
- Watch out: the weekly reports show 254 open issues, including 7 bugs
- Too light for modern web apps if you rely on the newest standards
Pick SeaMonkey if
- Fits if you want browser, mail and IRC in one desktop program
- Makes sense if you read newsgroups or edit HTML pages by hand
Look elsewhere if
- Skip it if you want a phone version, as the site offers no iOS or Android edition
- Not for you if you use an Apple silicon Mac, since only an x64 macOS build is listed
- Watch out: the current release listed is 2.53.24, built on the Gecko engine
- Too heavy if you only want to browse, since mail, chat and editor come along
How we grade them
| 3.0GPAOtter BrowserVery good | 3.0GPASeaMonkeyVery good | |
|---|---|---|
| Value for money | AFree software under GPL v3 with no paid plan, so under 60% of this category's cheapest quarter. | AFree, with donations and sponsors accepted and no paid plan, so it undercuts this category's $7 cheapest quarter. |
| Free plan and trial | AThe whole browser is free and open source, with no caps or paid tier. | AThe whole suite for Windows, macOS and Linux downloads at no charge, in 20-plus languages. |
| Features | CA customizable, lightweight browser for power users, with the basics but a small team behind it. | CBrowser, mail and news, feeds, IRC and an HTML editor in one program, built on Gecko. The browser itself is the same size of job as any other. |
| Ease of use | BNo rating on record. You install a binary or AppImage and use it, with options to tune if you want. | BNo rating on record. It is a program you install and start using, though a suite has more parts than a lone browser. |
| Platforms and integrations | CWindows and Linux are listed. The project's site does not name macOS or any phone version. | CWindows x64 and x86, macOS x64 and Linux x64 and x86 builds, with no Android or iOS edition. |
| Best for | a customizable browser in the Opera 12 style | an all-in-one browser, mail and chat suite |
The GPA is the average of the five grades: an A is 4 points, an F is none. The full reasons are on each tool's page: Otter Browser and SeaMonkey. How we grade
Price against what you get
Otter Browser has no paid plan and scores 2.3 out of 4 on features, ease of use and platforms. SeaMonkey has no paid plan and scores 2.3.
On this chart the two sit in the same place: the same score for the same starting price. Of the other browsers on the chart, none scores higher than Otter Browser for less, and none scores higher than SeaMonkey for less.
Features, ease of use and platforms, averaged
What paid plans start at, a month (each step along is roughly double) →
- The best score at each price
- Has a free plan
- No free plan
Where they differ
- SeaMonkey also covers email client and rSS reader.
At a glance
| Otter Browser | SeaMonkey | |
|---|---|---|
| Pricing | Free | Free |
| Starts at | Free | Free |
| Free plan | Free and open source under the GPL v3, with no paid plans. | SeaMonkey is free; the site accepts donations and sponsors and lists no paid plan. |
| Free trial | None listed | None listed |
| macOS | ||
| Windows | ||
| Linux | ||
| Made by | Otter Browser project | SeaMonkey Association |
| Price read from | github.com | seamonkey-project.org |
| Checked | Nov 13, 2026 | Nov 13, 2026 |
Worth knowing
Otter Browser
- The project's own site lists official binaries, with an AppImage for Linux and downloads for Windows on SourceForge; macOS is not named there.
- Development is slow: its recent weekly reports show about seven commits by one author each week.
- The weekly reports show 254 open issues, including 7 bugs.
SeaMonkey
- The listed macOS build is x64 only; no ARM-specific macOS build is shown.
- It is run by a community council, and the about page says it describes the only full internet suite still developed.
- The current release listed is 2.53.24, built on the Gecko engine.
- The site offers no iOS or Android edition.
Key features
Otter Browser
- Opera 12 style interface
- The project says it aims to recreate the best aspects of the classic Opera 12.x user interface and keep its spirit alive.
- Built with Qt
- The browser is written primarily in C++ and uses the Qt framework.
- Power-user focus
- The project says it focuses on features power users want while staying fast and lightweight.
- Free software
- Released under the GNU GPL v3, so anyone can read the code and contribute.
SeaMonkey
- Browser
- An Internet browser built on Gecko, the same code behind Thunderbird and the base of Firefox.
- Email and newsgroups
- A built-in mail and newsgroup client, plus feed reading, per the site's one-line description.
- IRC chat
- Chat is included in the same application as the browser and mail.
- HTML editor and web development tools
- An HTML editor and web development tools are part of the suite.
- Multiple languages and platforms
- The download table lists Windows x64 and x86, macOS x64, and Linux x64 and x86 builds in many languages.
Plans
Otter Browser
Free$0
The full browser, free software under GPL v3.
SeaMonkey
Free$0
The full suite for Windows, macOS and Linux, in 20-plus languages.
Common questions
Which is cheaper, Otter Browser or SeaMonkey?
As of Nov 13, 2026, both Otter Browser and SeaMonkey are free to use.
Which has a free plan, Otter Browser or SeaMonkey?
As of Nov 13, 2026, both Otter Browser and SeaMonkey have a free plan.
Which platforms do Otter Browser and SeaMonkey run on?
As of Nov 13, 2026, only SeaMonkey lists a macOS app. Both list Windows and Linux apps. A platform missing from a listing is one its maker's pages did not mention.
More comparisons
How this page was made
- The verdict at the top follows a fixed rule. When both tools are in the same category and either is in our top three for it, the verdict follows that ranking: the higher-placed tool is our pick. The top three weigh who each tool suits as well as its grades, so a pick can go against the GPA. Otherwise the page does not pick one and says which grades higher: the higher GPA first; on a tie, the one with a free plan, then the one that starts cheaper in dollars a month, counted the same way for both; if they are still level, what the choice depends on.
- The grades are our own, from each tool’s review or report card. The GPA is their average.
- Prices, plans and platforms come from each tool’s listing. The table above says where each price was read and when.
- The differences and the answers to the questions are worked out from those listings.