There is a quiet but consequential shift underway in the browser market, and it has nothing to do with artificial intelligence or privacy regulation. Mozilla's decision to enable split view by default in the Firefox 149 beta represents the organisation's most visible concession yet to a decade-long demand from power users: the ability to view two web pages simultaneously within a single browser window, without resorting to external tools or operating-system trickery.
The feature is not new in the strictest sense. As The Register reports, split view was first introduced in a hidden state in Firefox 146, released in early December 2025. Users running any version from 146 onwards have technically had access to it, provided they were willing to open the about:config settings panel and manually toggle browser.tabs.splitView.enabled from false to true. The Firefox 149 beta, which followed the stable release of Firefox 148 in late February, marks the first time Mozilla has switched the feature on by default, a signal that the organisation considers it ready for general audiences.
The mechanics are straightforward. Holding Ctrl (or Cmd on a Mac) and clicking a second tab selects both, after which a right-click on either tab reveals the option to open the pair in split view. The two panes scroll independently, share a single URL bar that reflects whichever pane currently has focus, and their tab buttons sit adjacently in the tab bar whether it is arranged horizontally or vertically. The separator between panes is draggable, permitting asymmetric layouts where one page occupies more screen real estate than the other. Mozilla plans to release Firefox 149 on 24 March 2026.
The strategic calculus here involves several competing considerations. The most obvious is competitive pressure. Zen Browser is a free and open-source fork of Mozilla Firefox introduced in 2024, with a focus on privacy, customisability, and design. Since The Browser Company announced that the Arc browser was no longer going to receive new features, Zen has been considered a major alternative and a continuation in spirit. Zen's built-in tiling capability was, for much of the past eighteen months, one of its clearest differentiators from its upstream parent. Mozilla's move to close that gap with a native implementation changes the competitive arithmetic, though the gap has not yet been eliminated.
What often goes unmentioned in coverage of Firefox's new feature is how much ground Mozilla still needs to cover. Zen's split view feature lets users open up to four tabs side by side simultaneously. Firefox's current implementation is limited to two panes and does not support three-column or 2x2 grid arrangements. There are also functional constraints: the panes do not behave as independent windows, so users cannot drag a link from one pane and drop it into the other, nor can they right-click a link and open it directly into a new pane. It has taken eighteen months for Mozilla to catch up even as far as two side-by-side pages. Zen, in the meantime, has continued to iterate, and Zen now runs on the Firefox 148 browser core, providing updated web standards and performance improvements inherited from the latest Mozilla release.
The broader context matters here. The arrival of native split view in a mainstream browser with hundreds of millions of users worldwide is not merely a feature addition; it is a validation of a workflow philosophy that tiling window manager enthusiasts and productivity-focused users have long advocated. While tiling window managers have long been a favourite among power users, bringing this capability directly into the browser democratises access to a more productive workflow. For users who do not run a tiling desktop environment or a dedicated window-snapping utility, Firefox's implementation requires no new software, no configuration of external tools, and no adjustment to existing habits beyond learning a single right-click option.
Split view is the headline addition, but the Firefox 149 beta release notes also document several less visible improvements. The beta also includes hardware-accelerated PDF rendering, address autofill for more countries, performance tweaks for WebGL on Windows, and easier sharing capabilities. These are incremental refinements rather than transformative changes, but they reflect Mozilla's continuing effort to sharpen performance across its increasingly diverse user base.
A word of caution is warranted for readers tempted to install the beta immediately. Running a beta version of Firefox will update the user's active browser profile to a format that older stable versions cannot read, effectively preventing a clean downgrade. Users wishing to test the beta safely should create a separate Firefox profile before launching it, or invoke the browser with the --allow-downgrade command-line switch when reverting. For those on current stable releases who simply want to try split view without touching the beta, the about:config toggle remains the safer path.
The evidence, though incomplete, suggests that Firefox's split view will satisfy the majority of users who wanted the feature without the overhead of switching browsers. Whether it is sufficient to slow Zen's momentum among the minority who require more sophisticated multi-pane arrangements is a different question. Zen retains a meaningful lead in layout flexibility, and its active development community continues to add features at a pace that a large organisation like Mozilla will find difficult to match cycle-for-cycle. Both browsers ultimately benefit from the competition, and users are better served by two capable alternatives than by a market where only one side is pushing the technology forward.