SigmaOS vs Arc

We make Yab, the third column.facts checked Oct 9 ↓

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.

Arc is The Browser Company’s Chromium browser for Mac and Windows that put tabs down the side, with spaces, folders and Split View. It has had no new features since May 2025; it still gets security fixes, and its makers point people to Dia.

Both put tabs down the side with workspaces. SigmaOS runs on WebKit and only on Macs, with no public release notes since February 2025; Arc gets security fixes only.

The short answer

Pick SigmaOS

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

Pick Arc

if you use it today and want its sidebar, spaces and Split View exactly as they are
if you want a free browser with no paid AI plans
if you need the same layout on Windows

Or Yabours

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 Arc, with Yab beside them for a Mac.

SigmaOS vs Arc
What	SigmaOS	Arc	Yab
Made by	SigmaOS Inc. (London)	The Browser Company (Atlassian)	Serafim Korablev
Status	No release notes since February 2025	Security fixes only	Updated
Runs on	Mac	Mac and Windows	Mac
Phone app	None; Mac only. iOS has been on its roadmap since 2021	Arc Search on iPhone, iPad and Android; on iPhone it shows your desktop spaces and pins	Not yet
Price	Free; Personal Pro $20/month or Personal Max $30/month for more AI	Free; its Arc Max AI helpers are free too	Free; its AI runs on your own Claude or ChatGPT plan
AI	Chat about pages, on its own AI service	Chat about pages, on its own AI service	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	Yes	Yes
Spaces	Yes	Yes	Yes
Split View	Yes	Yes	Yes
Extensions	Chrome Web Store	Chrome Web Store	Chrome Web Store
Ad blocker	Built in	No	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.

AIa matter of taste

Both have AI to ask about pages, and neither does the clicking for you. Airis chats about the page you are on, sums it up, looks things up and translates; no agent. Arc Max helpers tidy tab titles and downloads, preview links and put ChatGPT in the command bar; Ask on Page was removed in August 2025, and there is no agent.

Tabs and windowsArc leads

SigmaOS has tabs down the side, spaces and Split View. Arc has tabs down the side, spaces, Split View, folders in the sidebar and tabs that sleep.

PriceArc leads

SigmaOS: Free; Personal Pro $20/month or Personal Max $30/month for more AI. Arc: Free; its Arc Max AI helpers are free too.

Where it runsArc leads

SigmaOS runs on Mac. Arc runs on Mac and Windows. On a Mac, SigmaOS needs macOS 12 or later and Arc needs macOS 13 or later. SigmaOS has no phone app: Mac only. iOS has been on its roadmap since 2021. On the phone, Arc: Arc Search on iPhone, iPad and Android; on iPhone it shows your desktop spaces and pins.

Engine and extensionsa matter of taste

SigmaOS is built on WebKit, the engine Safari uses; Arc on Chromium, as Chrome is. Both take extensions from the Chrome Web Store.

PrivacySigmaOS 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. Arc has no ad blocker of its own. Arc needs an account; The Browser Company says it doesn’t see which sites you visit, and Arc Max sends page data to OpenAI and Anthropic.

UpdatesSigmaOS leads

SigmaOS: Still downloadable, with no public release notes since version 1.19 in February 2025. Arc: No new features since May 2025; Chromium security updates still come, the latest on October 8, 2026.

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

Arc

No new features since May 2025, only security updates
Needs an Arc account
No ad blocker of its own
On phones, Arc Search is a separate search app

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

October 21, 2025Arc: Atlassian completed its purchase of The Browser Company
August 28, 2025Arc: Ask On Page removed from Arc Max
May 26, 2025Arc: The Browser Company stopped feature work on Arc to focus on Dia
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 Arc free?

Yes. Free; its Arc Max AI helpers are free too.

Which has an AI agent, SigmaOS or Arc?

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. Arc Max helpers tidy tab titles and downloads, preview links and put ChatGPT in the command bar; Ask on Page was removed in August 2025, and there is no agent.

Which runs on Windows, SigmaOS or Arc?

Arc does. SigmaOS runs on Mac.

Do SigmaOS and Arc have phone apps?

SigmaOS has no phone app: Mac only. iOS has been on its roadmap since 2021. On the phone, Arc: Arc Search on iPhone, iPad and Android; on iPhone it shows your desktop spaces and pins.

Can I move from Arc to SigmaOS?

Yes: SigmaOS’s own help says it brings in from Arc.

Is SigmaOS still being updated?

Still downloadable, with no public release notes since version 1.19 in February 2025.

Is Arc still being updated?

No new features since May 2025; Chromium security updates still come, the latest on October 8, 2026.

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 vs Vivaldi SigmaOS vs Zen SigmaOS vs Orion SigmaOS vs Chrome SigmaOS vs Safari SigmaOS vs Edge SigmaOS vs Firefox SigmaOS alternatives Yab vs SigmaOS Vivaldi vs Arc Zen vs Arc Orion vs Arc Arc vs Chrome Arc vs Safari Arc vs Edge Arc vs Firefox Arc alternatives Yab vs Arc

Sources, read October 9, 2026. Something out of date? Write to hello@serafimlabs.io and we fix it.

Yab, Yet Another Browser.

Free for the Mac. Arc’s sidebar, your own Claude or ChatGPT as the agent, Chrome extensions on WebKit.

it’s freeMove from Arc Download