Mozilla Firefox 136, released in March 2025, represents a significant leap forward in browser innovation, combining user-centric design updates, enhanced privacy controls, and performance optimizations. This release introduces vertical tabs, a redesigned sidebar, and improved privacy features like HTTPS-First mode, while expanding language support for translations and offering native ARM64 builds for Linux. These changes reflect Mozilla’s ongoing commitment to balancing cutting-edge functionality with robust security, positioning Firefox as a compelling alternative in an increasingly competitive browser market.
User Interface Innovations
Vertical Tabs: Streamlining Tab Management
One of the most visually striking additions in Firefox 136 is the introduction of vertical tabs, a feature long requested by power users. By right-clicking the tab bar and selecting Turn on Vertical Tabs, the traditional horizontal tab strip shifts to a vertical column on the left side of the browser window. This layout prioritizes screen real estate for content, particularly beneficial for users managing numerous tabs simultaneously.
Vertical tabs default to favicon-only display, conserving space, but expand to show full titles when hovered over or toggled via a dedicated button. Early adopters report improved organization, as the vertical arrangement reduces visual clutter and simplifies navigation across tab-heavy workflows. The feature also supports resizing, allowing users to adjust the width of the tab strip to suit their preferences.
Redesigned Sidebar: Centralizing Browser Tools
Complementing the vertical tabs is a revamped sidebar that consolidates access to essential tools. The sidebar now houses bookmarks, browsing history, synced tabs from other devices, and integrated AI chatbots. This redesign aims to reduce reliance on disjointed menus, offering a unified hub for common tasks.
When vertical tabs are enabled, the sidebar buttons relocate to the bottom of the interface, creating a cohesive vertical workflow. Users can reposition the sidebar to the right or left and customize its visibility through a new toolbar icon. This update aligns with Mozilla’s broader strategy of enhancing accessibility while maintaining a clean, minimalist aesthetic.
Privacy and Security Enhancements
Enhanced Tracking Protection: Selective Unblocking
Firefox 136 refines its Enhanced Tracking Protection (ETP) strict mode by allowing selective unblocking of social media embeds. Previously, strict ETP settings could inadvertently break comment systems like Disqus. The update introduces granular controls, enabling users to permit specific embeds while maintaining broader tracking protections. Although initial support is limited to a handful of platforms, Mozilla plans to expand compatibility in future releases.
HTTPS-First Mode: Prioritizing Secure Connections
In a bid to bolster web security, Firefox 136 enables HTTPS-First mode by default. This feature attempts to establish secure HTTPS connections for all websites, falling back to HTTP only when encryption is unavailable. While HTTPS adoption has grown steadily, this change ensures that users benefit from encrypted connections wherever possible, mitigating risks associated with unsecured data transmission.
Certificate Transparency Enforcement
Building on Firefox 135’s security upgrades, version 136 enforces certificate transparency for all SSL/TLS certificates. This protocol requires certificate authorities to publicly log issued certificates, making it easier to detect malicious or misissued certificates. The update strengthens Firefox’s defenses against phishing and man-in-the-middle attacks, aligning with industry-wide efforts to improve cryptographic trust.
Performance and Platform Support
Native Linux ARM64 Builds
Firefox 136 marks a milestone for Linux users with the introduction of official ARM64 (AArch64) builds. This release caters to devices powered by ARM processors, such as Raspberry Pi 4 and newer Chromebooks, eliminating the need for emulation layers or third-party patches. The native builds promise improved performance and energy efficiency, particularly on low-power devices.
Hardware Acceleration Optimizations
Further performance gains come from enhanced video hardware decoding for AMD GPUs on Linux, enabled by default for systems running Mesa 24.2 or later. This optimization reduces CPU load during video playback, extending battery life on laptops and improving frame rates for high-resolution content. Additionally, macOS users benefit from improved resource management, as background tabs now leverage efficiency cores on Apple Silicon chips.
Productivity and Customization
Form Data Management and Autofill
Firefox 136 introduces granular control over saved form data, allowing users to clear autofill information independently of browsing history. This separation addresses privacy concerns while retaining convenience for frequently used forms. The update also expands address autofill support to the United Kingdom, building on existing regional implementations.
Image Copy as PNG
A subtle yet impactful change allows images copied from Firefox to be saved as PNG files by default, preserving transparency and quality. This adjustment benefits designers, developers, and content creators who rely on accurate visual representations, eliminating the need for manual format conversions.
Weather Widget Expansion
The New Tab Page weather widget, previously limited to select regions, now extends to Mexico, Brazil, Argentina, and Chile. This feature provides at-a-glance meteorological data tailored to the user’s location, enhancing personalization without compromising privacy.
Developer and Web Platform Updates
CookieStore API Integration
Firefox 136 adopts the CookieStore API, a modern JavaScript interface for managing cookies. This API simplifies cookie operations for developers, offering asynchronous methods and improved error handling. It also supports service workers, enabling more sophisticated offline capabilities in web applications.
Wayland Protocol Support
Linux users gain improved compatibility through the implementation of the wp_linux_dmabuf_feedback protocol, which optimizes buffer management for Wayland compositors. This update reduces latency in graphics rendering, particularly for applications utilizing hardware-accelerated video playback.
Conclusion
Mozilla Firefox 136 exemplifies the browser’s evolution as a privacy-first platform without sacrificing usability or performance. From vertical tabs empowering multitaskers to HTTPS-First mode safeguarding everyday browsing, each feature reflects a deliberate balance between innovation and user trust. The expansion into ARM64 Linux builds and enhanced developer tools further solidifies Firefox’s relevance in diverse computing ecosystems.
For users, upgrading to Firefox 136 is strongly recommended to leverage these advancements and ensure protection against emerging security threats. Those clinging to older versions, such as Firefox 113 (which loses add-on support in March 2025), should transition to supported releases or explore enterprise-focused alternatives like Firefox ESR. As the digital landscape grows increasingly complex, Firefox 136 stands as a testament to Mozilla’s vision of an open, secure, and user-empowered web.