YabYab, Yet Another Browser, is a free Mac browser that keeps everything from Arc (tabs down the side, spaces, folders, Split View) and gives your Claude or ChatGPT plan an agent that works in your signed-in tabs.
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.
The short answer
- 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
- if you want Claude Code, Codex or Cursor to drive a real browser over MCP
- 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
At a glance
Yab and SigmaOS, side by side.
| What | Yab | SigmaOS |
|---|---|---|
| Made by | Serafim Korablev | SigmaOS Inc. (London) |
| Status | Updated | No release notes since February 2025 |
| Runs on | Mac | Mac |
| Phone app | Not yet | None; Mac only. iOS has been on its roadmap since 2021 |
| Price | Free; its AI runs on your own Claude or ChatGPT plan | Free; Personal Pro $20/month or Personal Max $30/month for more AI |
| AI | An agent that works in pages, on your Claude or ChatGPT plan | Chat about pages, on its own AI service |
| Driven by outside agents | MCP and a command line | No |
| Engine | WebKit | WebKit |
| Tabs down the side | Yes | Yes |
| Spaces | Yes | Yes |
| Split View | Yes | Yes |
| Extensions | Chrome Web Store | Chrome Web Store |
| Ad blocker | Built in | Built in |
| Open source | 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.
AIYab leads
Only Yab has an agent that clicks, types and finishes tasks in your pages. Yab’s agent works in tabs of its own beside yours, signed in as you, on your Claude or ChatGPT plan; Send, Pay and Delete wait for your yes. Airis chats about the page you are on, sums it up, looks things up and translates; no agent. Yab runs on the Claude or ChatGPT plan you already pay for; the other on its own AI.
Agents like Claude Code and CodexYab leads
Yab can be driven over MCP and a command line, through yab mcp and the yab command, for Claude Code, Codex, Cursor and any MCP client. SigmaOS has no MCP server or command line for outside agents.
Tabs and windowsYab leads
Yab has tabs down the side, spaces, Split View, folders in the sidebar and tabs that sleep. SigmaOS has tabs down the side, spaces and Split View.
Priceeven
Yab: Free; its AI runs on your own Claude or ChatGPT plan. SigmaOS: Free; Personal Pro $20/month or Personal Max $30/month for more AI.
Where it runseven
Both run on Mac. On a Mac, Yab needs macOS 15.4 or later and SigmaOS needs macOS 12 or later. Yab has no phone app yet. SigmaOS has no phone app: Mac only. iOS has been on its roadmap since 2021.
Engine and extensionsa matter of taste
Both are built on WebKit, the engine Safari uses. Both take extensions from the Chrome Web Store.
Privacyeven
Both have an ad blocker built in. Yab has no account and no server of ours between you and your sites; what your agent reads goes to Anthropic or OpenAI under your account. 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.
UpdatesYab leads
Yab is updated as usual. SigmaOS: Still downloadable, with no public release notes since version 1.19 in February 2025.
Where SigmaOS is better
SigmaOS is the better pick if you:
- Want workspaces and tabs you mark done, on a Mac
- Browse by keyboard, with single-key shortcuts
- Prefer WebKit to Chromium and want spaces
The catch with each
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
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
- September 25, 2026Yab: First release
- February 4, 2025SigmaOS: Version 1.19.0, a performance update, the last release with public notes
Questions
Is Yab free?
Yes. Free; its AI runs on your own Claude or ChatGPT plan.
Is SigmaOS free?
Yes, with limits on its AI. Free; Personal Pro $20/month or Personal Max $30/month for more AI.
Which has an AI agent, Yab or SigmaOS?
Yab. Yab’s agent works in tabs of its own beside yours, signed in as you, on your Claude or ChatGPT plan; Send, Pay and Delete wait for your yes. Airis chats about the page you are on, sums it up, looks things up and translates; no agent.
Which runs on Windows, Yab or SigmaOS?
Neither. Yab runs on Mac; SigmaOS on Mac.
Do Yab and SigmaOS have phone apps?
Yab has no phone app yet. SigmaOS has no phone app: Mac only. iOS has been on its roadmap since 2021.
Is SigmaOS still being updated?
Still downloadable, with no public release notes since version 1.19 in February 2025.
More comparisons
- 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
- 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
Yab, Yet Another Browser.
Free for the Mac. Arc’s sidebar, your own Claude or ChatGPT as the agent, Chrome extensions on WebKit.