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Zen Browser

Developer(s)	Mauro (maubg)
Initial release	July 11th, 2024
Stable release(s)
Windows 1.0.2-b.3 (Beta) / December 19, 2024; 5 days ago (2024-12-19) macOS 1.0.2-b.3 (Beta) / December 19, 2024; 5 days ago (2024-12-19) Linux (Flatpak) 1.0.2-b.3 (Beta) / December 19, 2024; 5 days ago (2024-12-19)
Preview release(s)
Windows 1.0.2-t.4 (Experimental) / December 22, 2024; 2 days ago (2024-12-22) macOS 1.0.2-t.4 (Experimental) / December 22, 2024; 2 days ago (2024-12-22) Linux (Flatpak) 1.0.2-t.4 (Experimental) / December 22, 2024; 2 days ago (2024-12-22)
Repository	https://github.com/zen-browser/desktop
Written in	JavaScript, CSS, C++, HTML, Shell
Operating system	Microsoft Windows, macOS, Linux
License	Mozilla Public License 2.0
Website	https://zen-browser.app/

Zen Browser is a free and open-source fork of Mozilla Firefox, with its main focus being privacy and customizability, and it is licensed under the Mozilla Public License 2.0 (MPL 2.0).^[1][2]

Zen Browser started development on Αpril 1, 2024,^[3] after being mentioned in a Reddit post on r/browsers. On July 12, 2024, the first public release of Zen Browser was released as an Alpha build, named 1.0.0-a.1.^[4] As of now,^[when?] there are a total of 104 contributors to Zen Browser, 52 desktop contributors and 52 site contributors.^[5] Zen Browser also has a Twilight build,^[6] an unstable experimental build for testing the latest features. On December 10, 2024, Zen entered its beta phase, and launched its new "Zen" branding, featuring a new logo and a new website, with its new tagline: "Welcome to a calmer internet".

Zen Browser is compatible with Microsoft Windows, macOS and Linux. It had three download options: optimized, made for newer systems; generic, made for older systems; and ARM64, made for devices that run on ARM64 architectures. The optimized version used Advanced Vector Extensions 2 (AVX2), a CPU instruction set that enhances performance for certain tasks. This instruction set is available only on modern processors.^[7] The optimized builds were discontinued in December 2024 due to high power consumption, user confusion, and incompatibility with other Clang optimizations.^[8]

The optimized builds of Zen Browser are compatible only with the following CPU families:

• AMD
  • Carrizo
  • Bristol Ridge
  • All Ryzen CPUs
• Intel
  • Desktop and Mobile Processors
    • 4th generation Intel Core and newer (All architectures)
    • Celeron and Pentium Tiger Lake and newer
    • Intel Core Series 1 and Series 2
  • High-End Desktop (HEDT) and Server Processors
    • Intel Core X-series (Skylake X, Cascade Lake)
    • Xeon Scalable (Cascade Lake)
    • Xeon Scalable (Cooper Lake)
    • 3rd generation Intel Xeon Scalable (Ice Lake, Cooper Lake)
    • 4th generation Intel Xeon Scalable (Sapphire Rapids)
    • 5th generation Intel Xeon Scalable (Emerald Rapids)

The Linux version is available for download as a Flatpak or as an AppImage. The macOS version is available for both AArch64 and Intel.

Zen Browser adopts the vertical tabs philosophy, which has been observed in other browsers like Vivaldi, Microsoft Edge and Brave, and is especially prominent in Arc Browser. Similar to Arc, vertical tabs are central to Zen's identity, but there are plans to implement horizontal tabs like a traditional browser in a future release.^{[9][better source needed]}

Zen Browser has many distinct features, like Split View, which allows you to split any number of websites into multiple tiled panes inside a single window; Zen Sidebar, a built-in detachable sidebar for quickly opening websites side-by-side; and Zen Glance, a feature to quickly preview a website without leaving your current page.

However, Zen Browser currently lacks DRM-support, because it does not have a Widevine license. The developer has stated that acquiring such a license requires the payment of large fees and is therefore unfeasible. This means that DRM-protected media cannot be played in Zen Browser for the foreseeable future,^[10] which may limit access to some streaming services and DRM-protected content.^[11]

Liam Proven from The Register praised Zen Browser for being a Google-free browser.^[12]

Jack Wallen of ZDNet praised Zen for being the "customizable Firefox".^[13]

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Zen Mods (formerly called Themes Store) is a Zen Browser feature which uses custom made UGC themes which can only be compatible with Zen. As of December 10, 2024, the theme store has 75 total themes, further adding to the customizability.

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Zen Browser has several security features to protect user data and privacy:

• Built on Latest Firefox Version: Zen Browser is based on the most recent version of Firefox, benefiting from Firefox's security updates and patches.
• Tracking Protection: The browser includes tracking protection, blocking third parties from tracking users' online activities.
• OCSP Support: Zen Browser uses the Online Certificate Status Protocol (OCSP) to verify the validity of websites' SSL certificates, enhancing security against expired or revoked certificates.
• HTTPS-Only Mode: Zen Browser attempts to connect to websites over HTTPS whenever possible, encrypting communication between the user and the website.
• Strict SSL Standards: Insecure SSL connections are treated as broken by default, and Zen Browser blocks connections to websites that do not meet modern security standards.