Mozilla Firefox vs Zen Browser in 2026

Zen Browser exists because people wanted Arc's interface without leaving Firefox's engine. It takes Gecko and the privacy work that comes with it, then rebuilds the shell around workspaces, split view and a sidebar. The interesting part in 2026 is that Firefox has closed some of that gap on its own, which changes what Zen is actually for.

What Zen still does that Firefox does not

Split view is the clearest one: Zen tiles up to four tabs in a grid, and Firefox has no equivalent without an extension. Workspaces separate contexts more thoroughly than tab groups do, Zen Glance previews a link without leaving the page, and Mods let you restyle the interface. The whole thing is designed around reducing visual noise, and it is unusually coherent for a young project.

Firefox added native vertical tabs in version 136 and tab groups shortly after, so two things Zen was known for are no longer exclusive. Both score 4 for privacy, both block trackers and resist fingerprinting, and both sync through a Mozilla account — Zen uses Firefox Sync directly.

Where Firefox is still ahead

Reach and maturity. Firefox runs on all five major platforms; Zen is desktop only, so your phone needs a different browser. Firefox scores 5 for customizability against Zen's 4 and 5 for extensions against 4, and its configuration layer goes deeper than anything Zen exposes.

There is also the question of age. Firefox has two decades of hardening behind it and a large organisation shipping security updates on a two-week cadence. Zen is a small project tracking Firefox releases, and you occasionally meet a rough edge that a browser this young is entitled to have.

Which should you choose?

Choose Firefox if you want the same engine and privacy posture with mobile apps, the deepest configuration layer available, and the reassurance of a large team behind the updates. Now that vertical tabs and tab groups have landed, the interface gap is narrower than it was a year ago.

Choose Zen Browser if split view and workspaces are how you actually work and you browse on desktop only. It is the most convincing attempt anyone has made at Arc's interface on Gecko, and it costs you nothing in privacy to try — but keep Firefox on your phone, because Zen cannot go there.