Dia vs Zen Browser in 2026

When The Browser Company announced that Arc stops working on December 22, 2026, its users went two ways. Some followed the team to Dia, the company's AI browser. Others moved to Zen Browser, an open-source Firefox fork that kept the sidebar and Spaces Arc made popular. On the question that defines browsers in 2026, the two could hardly be further apart: Dia scores 5 for AI features in our ratings, and Zen scores 1 because it ships no AI.

What each keeps from Arc

Zen is the closer match to how Arc felt. It has a vertical sidebar, Spaces that keep separate contexts in one window (each with its own container if you want it), split view for up to four tabs, Glance for previewing links, and a compact mode that hides the interface until you need it. Since version 1.24b, released on October 29, 2026, it can import Spaces and profiles from Arc, and from Dia too. It scores 4 for customizability against Dia's 3.

Dia comes from Arc's own team, and its importer brings over Arc's passwords, bookmarks, history, extensions and tabs. It deliberately does not reproduce Arc's Spaces model, though. The interface is stripped back so the page dominates. Vertical tabs, split view and tab groups are all there, but organising your browsing is not the point.

AI or no AI

The assistant is Dia's reason to exist. It reads the page you are on and any tab you mention, answers questions about your browsing history, and runs saved prompts called Skills. Paid plans connect it to Slack, Google Workspace and Atlassian's tools, which fits its owner: Atlassian bought The Browser Company in a deal announced in September 2025 and wants Dia to be a browser for work. Dia keeps chats and history encrypted on your device, but when you ask something, page content goes through its servers to cloud AI providers.

Zen has no AI to opt out of. For many of the people who pick it, that is the appeal, and it helps explain why Zen scores 4 for privacy against Dia's 3. Both block trackers, but Zen also inherits Firefox's fingerprinting protection, which Dia lacks in our feature table, and it is fully open source, where Dia is closed.

Engines and extensions

Dia runs Chromium and installs Chrome Web Store extensions, so sites built and tested for Chrome behave as expected. Zen runs Firefox's Gecko engine and installs Firefox add-ons, including the full version of uBlock Origin, which Manifest V3 restricts on Chromium browsers. Zen scores 4 for extensions against Dia's 3.

Price, platforms and maturity

Zen is free, with no paid tier. Dia's browser is free too, but since August 2026 new Mac users get a 14-day trial and then need Better Answers at $10 a month or Better Days at $100 a month to keep the AI. Existing users kept their free access, and the Windows version had no paid plans at the time of writing.

Zen runs on Mac, Windows and Linux. Dia runs on Mac and, since October 2026, Windows 11. Neither has a phone app. Both are young: Zen still labels its releases beta, and Dia's Windows version is less mature than its Mac app. They score the same for speed and ease of use, 4 each.

Which should you choose?

Choose Dia if you want to stay with the team that made Arc, you work on a Mac or Windows PC, and an assistant that reads your tabs is something you would pay for.

Choose Zen Browser if what you loved about Arc was the sidebar and Spaces, you want no AI in your browser, or you use Linux. It is the closer replacement for Arc, it costs nothing, and because it is open source, its code would outlive the project if development ever stopped.