Zen Browser, Firefox, Brave, and Arc are four of the most-compared browsers in 2026, and they split cleanly on one thing: the engine. This head-to-head shows how they differ on privacy, features, and platform support, so you can pick the right one instead of switching twice.
Reviewed by the Get ZEN editorial team, last updated July 2026. We test browsers on Windows, macOS, and Linux and verify feature claims against each project's official documentation before publishing.
The Core Split: Chromium vs Gecko
The biggest difference is the engine underneath. Zen and Firefox use Mozilla's Gecko engine. Brave and Arc use Google's Chromium engine. That single fact shapes privacy, ad blocking, and how much you help Google's grip on the web. If avoiding Chromium matters to you, the choice is already half made.
Zen vs Firefox vs Brave vs Arc: Full Comparison
| Criteria | Zen | Firefox | Brave | Arc |
|---|---|---|---|---|
| Engine | Gecko | Gecko | Chromium | Chromium |
| Interface | Arc-style workspaces | Classic tabs | Classic tabs | Sidebar workspaces |
| Built-in ad block | No (add uBlock Origin) | Tracking protection only | Yes | No |
| Telemetry | None | On by default | Some | Some |
| Mobile app | No (desktop only) | Yes (Android, iOS) | Yes | Yes (iOS, Android) |
| Active development | Yes | Yes | Yes | Maintenance only (see below) |
| Open source | Yes (MPL 2.0) | Yes | Yes | No |
| Price | Free | Free | Free | Free |
Is Zen Browser Just Arc?
No, Zen Browser is not just Arc. Zen copies Arc's workspace idea — vertical tabs, split view, and a clean sidebar — but it runs on Firefox's Gecko engine, while Arc runs on Chromium. Zen is also fully open source, and Arc is not. So Zen looks like Arc but is built on a different, more private foundation.
Is Zen Browser Just Firefox?
No, Zen Browser is not just Firefox with a skin. Zen shares Firefox's engine and extension support, but adds a very different interface built for workspaces and multitasking, and it strips the telemetry Firefox ships. Think of Zen as Firefox's engine wearing Arc's clothes.
When to Choose Each Browser
Choose Zen for Arc-style organization without Chromium, on desktop. Choose Firefox when you need one browser across desktop and phone with full sync. Choose Brave if you want built-in ad blocking and do not mind Chromium. Choose Arc only if you specifically want its design and accept a closed-source Chromium base — note that The Browser Company put Arc into maintenance mode in 2025 and shifted new development to its successor, Dia, so Arc gets fixes but few new features. For the full field of Gecko options, see our Firefox forks comparison, and for the deep dive on Zen itself, read our Zen Browser review.