Mozilla Firefox vs Sleipnir
Mozilla Firefox
firefox.com
Sleipnir
fenrir-inc.comSide by side
| Figure | Mozilla Firefox | Sleipnir |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | Yes | — |
| Web | Yes | — |
| Windows | Yes | Yes |
| macOS | Yes | Yes |
| Linux | Yes | — |
| iOS | Yes | Yes |
| Android | Yes | Yes |
| Plans published | 1 | 2 |
| Spec score · Web browsers | 9.0 (#11) | 8.7 (#27) |
| Browser engine | gecko | chromium |
| Built-in ad blocking | Yes | Yes |
| Cross-device sync | Yes | Yes |
| Extensions | Firefox extensions add browser features and tools, with thousands of free extensions available through addons.mozilla.org. | Chrome extensions are supported on the Windows version; the Mac version currently does not support extensions. |
| Extension support | own_store | chrome_store |
| Founded | 2004 | 2002 |
| Free plan | Yes | Yes |
| Supported platforms | both | both |
| Privacy | Firefox's privacy notice says browsing history, form data, temporary files and cookies are processed on the device unless the notice says otherwise. | The maker says recommended articles are generated locally, so they do not raise privacy concerns. |
| Product | Firefox is a web browser that Mozilla describes as fast, private and useful across devices. | Sleipnir 6 is a web browser designed for Windows and Mac. |
| Security | Firefox uses Google Safe Browsing to protect against malicious downloads and phishing attacks, and validates web pages and technical data with certificate authorities. | Fenrir's company security policy describes operating, monitoring, reviewing, maintaining, and continually improving its security management system. |
| Support | Mozilla provides Firefox help resources for desktop, enterprise, Android and iOS. | Fenrir directs visitors to its email form for inquiries and notes it may not be able to respond by phone. |
Plans
In their own words
Mozilla Firefox
Mozilla Firefox is a free, open-source web browser that uses the Gecko engine. It is available on Windows, macOS, Linux, iOS, Android, and as a browser extension, and its download page lists availability in more than 90 languages. Standard tracking protection and built-in ad blocking are included. Total Cookie Protection isolates cookies so they cannot follow users between websites, while Tab Groups organize open tabs by project, mood, or task. A Mozilla account can sync bookmarks, passwords, and open tabs across devices. Firefox also offers access to multiple AI chatbots in one place, letting users choose whether to use them. Thousands of free extensions are available through addons.mozilla.org. Mozilla’s privacy notice says browsing history, form data, temporary files, and cookies are processed on the device unless stated otherwise. Automated translation and PDF alt-text suggestions use downloaded language models locally; Firefox says those features do not send page content, PDFs, images, or tab URLs to Mozilla. Firefox is listed at free.