Why Rio is open source
Rio is open source under GPL-3.0, and its code is public on GitHub. Anyone can read what it does, build it from source and keep it going, so nobody can shut it down on you. Anyone who ships a browser built on Rio has to publish their code under GPL-3.0 too.
Why I made it open
I ran my whole day in Arc: 4 spaces, 38 pinned tabs, 29 favorites. In May 2025 The Browser Company stopped adding features to Arc, and in the same letter it said it couldn't open-source Arc without also open-sourcing ADK, the engine its next browser runs on. On October 22, 2026 Arc's help center set the end date. On December 22, 2026 Arc stops working, and Arc's own page says you won't be able to open it to get to your spaces and tabs after that.
Everyone who had built their day in Arc got the same news on the same day, and none of us had a say in it. When I built Rio, I wanted the people who move their day into it to have something they could do: take the code and keep going.
What open source means for Rio
Rio's code is public on GitHub under GPL-3.0. In practice:
- You can read it. What Rio sends and what the Arc import touches can both be checked against the code.
- You can build it. The README walks through building Rio from source.
- You can keep it going. If you want Rio to work differently, fork it. The code stays public for anyone to pick up.
Rio also has no account. There is no login to deactivate and no data on a server to delete. Your tabs, history and passwords sit in Rio's profile on your Mac.
What GPL-3.0 asks of others
GPL-3.0 keeps Rio open for everyone downstream. You can use Rio, change it and share it. If you distribute a browser built on Rio, you release its source under GPL-3.0 too. Rio's README also asks forks to use their own name, bundle id and update feed, so nobody mistakes a fork's updates for Rio's.
So a company can't take Rio, close the source and ship it as its own closed browser.
What is in the repository
chromium/: Rio's own Chromium-side code and its patches against Chromiumsrc/renderer: the interface you see, the sidebar, command bar and settingssrc/shared: the shared rules, including the key table that sets every keyboard shortcut- Tests next to the code, from unit tests to tests that drive the interface
Rio is built on Chromium 158, the open-source project Chrome is built from, so pages render as they do in Chrome and Chrome Web Store extensions work.
No hidden switches
Rio's contributing guide has a rule I care about: no feature flags or hidden toggles. A feature either ships on for everyone or it isn't merged. There is no version of Rio with features switched on for some people and off for others.
Taking part
- Report a bug on GitHub issues. The form asks for your macOS version and Rio's version from About Rio. In Rio, Help, Report a Problem opens the same form with both filled in.
- Ask a question or share an idea in GitHub Discussions.
- Report a security problem privately from the repository's Security tab.
- Send a change. The contributing guide asks for one change per pull request, with tests next to the code.
Every release and its notes are public too, on rio-releases and in the changelog. Since build 1446, each release is signed with a Developer ID and notarized by Apple.
Questions
Is Rio free?
Yes. It's free to use, and the code is open source under GPL-3.0.
Where is Rio's source code?
On GitHub at github.com/Levivajan/rio. Releases and the update feed are at github.com/Levivajan/rio-releases.
Can I build a product on Rio?
Yes, if you release it under GPL-3.0 too. Rename it and use your own bundle id and update feed.
How do I report a security problem?
Privately, through GitHub. Open the Security tab of github.com/Levivajan/rio and choose Report a vulnerability. Please don't open a public issue for it.
