Rio vs Zen
Rio and Zen are free, open-source browsers with tabs in a sidebar grouped into spaces. Rio is built on Chromium 158 and runs Chrome Web Store extensions, including Chrome side panel extensions; Zen is built on Firefox. Rio's Arc import brings spaces, pinned tabs, folders, favorites, history, saved passwords and sign-ins in one step.
Side by side
| Rio | Zen | |
|---|---|---|
| License | GPL-3.0 | MPL-2.0 |
| Price | Free | Free |
| Extensions | Chrome Web Store, Manifest V3 included | Firefox add-ons from addons.mozilla.org |
| Sidebar grouping | Spaces with pinned tabs, folders, favorites and Today tabs | Workspaces |
| Two pages at once | Split view, 2 to 4 panes | Split view |
| Quick look at a link | Peek, Shift-click a link | Glance, Option-click (Alt) a link |
| Arc import | Spaces, profiles, pinned tabs, folders, favorites, Today tabs, bookmarks, history, passwords, sign-ins | Spaces and Profiles from Arc and Dia, since 1.24b |
| Latest release | Build 1446, November 12, 2026 | 1.24.2b, November 11, 2026 |
Where Rio is ahead
- Chrome extensions. Rio installs from the Chrome Web Store, and Chrome side panel extensions open next to the page. If an extension you rely on is published only there, Rio can install it. Zen's documented source for extensions is addons.mozilla.org.
- The Arc import goes further. Zen's release notes list Spaces and Profiles. Rio also brings pinned tabs, folders, favorites, Today tabs, bookmarks, history, saved passwords and sign-ins, so sites stay logged in.
- Speedometer 3.1. Rio scored 97.8 against Chrome on our Mac. BrowseRating's scores put Zen at 76.8% of its Chrome score, and a run quoted in Aside's post puts it at 83.2%, each on another Mac. We have not run Zen ourselves.
Who Rio is for
People who rely on Chrome extensions and want their Arc setup brought over with its pinned tabs and logins.
Questions
Which is better for Chrome extensions, Rio or Zen?
Rio. It is built on Chromium and installs extensions from the Chrome Web Store, including Chrome side panel extensions. Zen is built on Firefox and installs add-ons from addons.mozilla.org, Firefox's add-on site.
Does Zen import from Arc?
Yes. Zen 1.24b (October 29, 2026) added import of Spaces and Profiles from Arc and Dia. Rio's Arc import also brings pinned tabs, folders, favorites, Today tabs, bookmarks, history, saved passwords and sign-ins.
Which one is faster?
Rio's Speedometer 3.1 index is 97.8 against Chrome on our Mac. BrowseRating's scores put Zen 1.23b at 76.8% of its Chrome score, and a run quoted in a post by the Aside browser's developers puts it at 83.2%, each on a different Mac.
Sources
- Zen on GitHub: Firefox-based, MPL-2.0
- Zen website: workspaces, compact mode, Glance, split view
- Zen 1.24b release notes: import Spaces and Profiles from Arc and Dia (October 29, 2026)
- Zen 1.24.2b release (November 11, 2026)
- Zen docs, Extensions: add-ons from addons.mozilla.org
- Zen docs, Glance
- BrowseRating, macOS ARM Speedometer 3.1 rankings (October 3, 2026)
- Aside, What Speedometer 3.1 actually measured (August 14, 2026)
- Chrome for Developers, chrome.sidePanel (Chrome 114 and later)
- Rio releases on GitHub
