YabSigmaOS vs Vivaldi
SigmaOS is a Mac browser on WebKit that treats tabs like a to-do list, in workspaces down the side, with an AI assistant called Airis.
Vivaldi is a Chromium browser with a setting for nearly everything, mail, calendar and feeds built in, a free Proton VPN and no AI by design, on every desktop and phone.
The short answer
- if you want workspaces and tabs you mark done, on a Mac
- if you browse by keyboard, with single-key shortcuts
- if you prefer WebKit to Chromium and want spaces
- if you want mail, calendar, feeds, notes and a VPN in the browser
- if you want to customize nearly everything, and no AI
- if you need one browser on Mac, Windows, Linux, iPhone and Android
- if you miss Arc and want spaces, pins and folders kept, on a Mac
- if you already pay for Claude or ChatGPT and want it to work in your signed-in tabs
At a glance
SigmaOS and Vivaldi, with Yab beside them for a Mac.
| What | SigmaOS | Vivaldi | Yab |
|---|---|---|---|
| Made by | SigmaOS Inc. (London) | Vivaldi Technologies | Serafim Korablev |
| Status | No release notes since February 2025 | Updated | Updated |
| Runs on | Mac | Mac, Windows, Linux, iPhone and Android | Mac |
| Phone app | None; Mac only. iOS has been on its roadmap since 2021 | iPhone, iPad and Android; syncs tabs, bookmarks, passwords, history and notes | Not yet |
| Price | Free; Personal Pro $20/month or Personal Max $30/month for more AI | Free; its Proton VPN is free with a Vivaldi account | Free; its AI runs on your own Claude or ChatGPT plan |
| AI | Chat about pages, on its own AI service | No AI | An agent that works in pages, on your Claude or ChatGPT plan |
| Driven by outside agents | No | No | MCP and a command line |
| Engine | WebKit | Chromium | WebKit |
| Tabs down the side | Yes | A setting | Yes |
| Spaces | Yes | Yes | Yes |
| Split View | Yes | Yes | Yes |
| Extensions | Chrome Web Store | Chrome Web Store | Chrome Web Store |
| Ad blocker | Built in | Built in | Built in |
| Open source | No | No | No |
Checked October 9, 2026 on each maker’s own pages, linked under Sources. Prices are per month, in US dollars.
Where they differ
What separates them, area by area. Where one plainly has more, it says who; where it comes down to taste, it says so.
AISigmaOS leads
SigmaOS has AI built in; Vivaldi has less of it. Airis chats about the page you are on, sums it up, looks things up and translates; no agent. Vivaldi has no AI chat, summaries or agents, by choice.
Tabs and windowseven
SigmaOS has tabs down the side, spaces and Split View. Vivaldi has tabs down the side as a setting, spaces, Split View, folders in the sidebar and tabs that sleep.
PriceSigmaOS leads
SigmaOS: Free; Personal Pro $20/month or Personal Max $30/month for more AI. Vivaldi: Free; its Proton VPN is free with a Vivaldi account.
Where it runsVivaldi leads
SigmaOS runs on Mac. Vivaldi runs on Mac, Windows, Linux, iPhone and Android. On a Mac, SigmaOS needs macOS 12 or later and Vivaldi needs macOS 13 or later. SigmaOS has no phone app: Mac only. iOS has been on its roadmap since 2021. On the phone, Vivaldi: iPhone, iPad and Android; syncs tabs, bookmarks, passwords, history and notes.
Engine and extensionsa matter of taste
SigmaOS is built on WebKit, the engine Safari uses; Vivaldi on Chromium, as Chrome is. Both take extensions from the Chrome Web Store.
PrivacyVivaldi leads
SigmaOS has an ad blocker built in. SigmaOS keeps history and cookies on your Mac unless you turn on sync, stored encrypted on AWS; its privacy policy doesn’t say where Airis requests go. Vivaldi has an ad blocker built in and a VPN. Vivaldi sends a daily ping with a unique ID, version and rough location to count users; crash logs only if you opt in.
UpdatesVivaldi leads
SigmaOS: Still downloadable, with no public release notes since version 1.19 in February 2025. Vivaldi is updated as usual.
What their pages don’t lead with
Real limits, from the makers’ own words and our own use.
SigmaOS
- Mac only
- No public release notes since version 1.19 in February 2025
- Chrome extensions only partly work, behind its WebKit+ option
- Its AI is an assistant, and regular use needs the $20 or $30 plans
Vivaldi
- No AI assistant or agent, by design
- Tabs down the side are a setting, not the default
- Its interface code isn’t open source
- Sends a daily usage ping with a unique ID
Yab, honestly
- Mac only: macOS 15.4 or later, no Windows, iPhone or Android
- New: first released in September 2026
- Its AI needs a Claude or ChatGPT plan; ChatGPT’s free plan may work with low limits
- WebKit, as in Safari: a site tested only in Chrome can misbehave
- Closed source
What changed lately
- May 21, 2026Vivaldi: Vivaldi 8.0 redesigned the interface
- January 29, 2026Vivaldi: Vivaldi 7.8 restated its no-AI stance
- March 27, 2025Vivaldi: Proton VPN built into Vivaldi on desktop
- February 4, 2025SigmaOS: Version 1.19.0, a performance update, the last release with public notes
Questions
Is SigmaOS free?
Yes, with limits on its AI. Free; Personal Pro $20/month or Personal Max $30/month for more AI.
Is Vivaldi free?
Yes. Free; its Proton VPN is free with a Vivaldi account.
Which has an AI agent, SigmaOS or Vivaldi?
Neither has an agent that does tasks in your pages. Airis chats about the page you are on, sums it up, looks things up and translates; no agent. Vivaldi has no AI chat, summaries or agents, by choice.
Which runs on Windows, SigmaOS or Vivaldi?
Vivaldi does. SigmaOS runs on Mac.
Do SigmaOS and Vivaldi have phone apps?
Vivaldi does. SigmaOS has no phone app: Mac only. iOS has been on its roadmap since 2021. On the phone, Vivaldi: iPhone, iPad and Android; syncs tabs, bookmarks, passwords, history and notes.
Can I move from Vivaldi to SigmaOS?
Yes: SigmaOS’s own help says it brings in from Vivaldi.
Is SigmaOS still being updated?
Still downloadable, with no public release notes since version 1.19 in February 2025.
Is there a third option on a Mac?
Yab, Yet Another Browser, is free for the Mac: tabs down the side with spaces, folders and Split View, as in SigmaOS; an agent that works in your signed-in tabs, on the Claude or ChatGPT plan you already pay for. Claude Code, Codex and any MCP client can drive it too. It runs on WebKit, the engine Safari uses, and takes Chrome extensions. It is Mac only, and new.
More comparisons
- SigmaOS home page
- SigmaOS upgrade (plans)
- SigmaOS download (macOS only)
- SigmaOS update feed (appcast)
- SigmaOS 1.19.0 update notes
- SigmaOS 1.17.0 update notes (password manager)
- SigmaOS common questions
- SigmaOS docs: ad blockers and WebKit+
- SigmaOS docs: migrating from Arc
- SigmaOS privacy policy
- TechCrunch: SigmaOS turns to AI features for monetization (2024-03-26)
- Launch HN (Aug 16, 2021): founder says iOS and iPadOS are on the roadmap
- Vivaldi features
- Vivaldi download (macOS 13+, universal; Windows, Linux, Android, iOS)
- Vivaldi macOS update feed (8.2.4133.84, minimum 13.0)
- Vivaldi desktop releases
- Vivaldi 8.2 release
- Vivaldi 8.0 release
- Vivaldi 7.8 release (no AI)
- Proton VPN built into Vivaldi, 2025-03-27
- Proton VPN for Vivaldi help
- Vivaldi tracker and ad blocker
- Vivaldi Memory Saver (automatic tab hibernation)
- Vivaldi Workspaces
- Vivaldi Tab Tiling
- Vivaldi Tab Stacks
- Vivaldi Tab Bar position
- Vivaldi import and export
- Is Vivaldi open source?
- Vivaldi browser privacy policy
- Vivaldi Help: Sync browser data on iOS
- Vivaldi Help: Sync browser data on Android
- Vivaldi blog: Introducing Vivaldi on iOS (Sep 28, 2023)
- Vivaldi on the App Store (iPhone and iPad)
- Vivaldi on Google Play
- Yab Manual: Bringing in from another browser
- Yab Manual: Connecting Claude or ChatGPT
- Yab Manual: Extensions
- Yab Manual: Yab’s tools over MCP
- Yab Manual: Privacy
Yab, Yet Another Browser.
Free for the Mac. Arc’s sidebar, your own Claude or ChatGPT as the agent, Chrome extensions on WebKit.