Verified Sep 2026

ActiveWebKit engine 25/30 documented

SigmaOS

A macOS-first WebKit browser that organises pages as tasks in a keyboard-driven workspace rather than as tabs.

Published by SigmaOS (United Kingdom) · Verified September 2026

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Runs on

macOSmacOS: Available
WindowsWindows: Unavailable
LinuxLinux: Unavailable
AndroidAndroid: Unavailable
iOSiOS: Unavailable

Choose it when

Choose SigmaOS on a Mac if you think in tasks rather than tabs and will invest in learning a keyboard-first interface.

Avoid it when

Avoid it if you need Windows, Linux, or mobile, or if you want a browser that behaves the way every other browser behaves.

Quick answers

Read straight off the verified record - every one of these is expanded with its source below.

Which platforms does SigmaOS run on?: Documented on macOS. Not available on Windows, Linux, Android, and iOS.
Can I install Chrome extensions?: Partly - Chrome Web Store support is conditional.
Does it block trackers out of the box?: Yes - tracker or ad blocking is on by default. The vendor cites WebKit Intelligent Tracking Prevention as part of the browser.
Does it have built-in AI features?: Yes - 3 of 9 documented AI capabilities are built in.
Is it open source?: Proprietary browser built on WebKit
Is it still being developed?: Active - Actively developed for macOS with a small team and a freemium model.

What SigmaOS does

Open any row for the wording and the source behind it

Privacy and tracking

1 built in · 1 partial · 1 not available · 1 undocumented

Blocks trackers by defaultBlocks trackers by default: Built in
The vendor cites WebKit Intelligent Tracking Prevention as part of the browser.
Anti-fingerprintingAnti-fingerprinting: Unknown
Telemetry postureTelemetry posture: Minimal or opt-in
The privacy policy documents account and engagement data, and states web activity stays local unless the user consents.
Built-in VPN or proxyBuilt-in VPN or proxy: Unavailable
Private windowsA Private Workspace is documented as storing no history and deleting its cookies automatically.
A Private Workspace is documented as storing no history and deleting its cookies automatically.
Default search engineConfigurable between DuckDuckGo, Ecosia, You.com, Bing, or a custom engine
Configurable between DuckDuckGo, Ecosia, You.com, Bing, or a custom engine

Extensions and blocking

1 partial · 1 not available · 3 undocumented

Chrome Web StoreChrome Web Store: Partial
Firefox Add-onsFirefox Add-ons: Unsupported
Native content blockingNative content blocking: Unknown
Pricing copy lists a built-in ad blocker while the documentation routes ad blocking through extensions; the default is not stated.
Manifest V3Manifest V3: Unknown
Manifest policy is not documented.
Manifest V2Manifest V2: Unknown
Manifest policy is not documented.
Known limitationsSome Chromium extensions are claimed to work on a WebKit base, so compatibility should be tested per extension.
Some Chromium extensions are claimed to work on a WebKit base, so compatibility should be tested per extension.

Workflow

9 built in · 1 partial · 1 undocumented

Vertical tabsVertical tabs: Built in
Pages are listed vertically in the left sidebar in place of a tab strip.
Tab treesTab trees: Built in
Pages can be indented and outdented into subpages.
Workspaces or spacesWorkspaces or spaces: Built in
Workspaces are the organising concept.
ProfilesProfiles: Built in
Profiles or equivalent browser identities are available.
Split viewSplit view: Built in
Side-by-side viewing is documented.
SidebarSidebar: Built in
A sidebar replaces the conventional tab strip.
Reader modeReader mode: Unknown
Reader mode is not documented.
Command paletteCommand palette: Built in
Lazy Search and a commands filter are documented keyboard entry points.
Sync across devicesSync across devices: Minimal or opt-in
Cloud sync is documented as deactivated by default and encrypted when enabled.
TranslationTranslation: Built in
A built-in translation feature is documented.
Progressive web appsProgressive web apps: Built in
Progressive web apps are supported by the Chromium install flow.

AI features

3 built in · 1 partial · 4 not available · 1 undocumented

Built-in assistantBuilt-in assistant: Built in
An assistant (Airis) is documented as part of the product.
Page summarisationPage summarisation: Unknown
Summarisation scope is not clearly documented.
Acts on pages for youActs on pages for you: Unavailable
AI answer engineAI answer engine: Built in
Airis Look it up searches the web and returns synthesized answers.
Works across open tabsWorks across open tabs: Unavailable
Text or image generationText or image generation: Built in
Airis rewrites text and generates outlines and summaries in-page.
Choice of modelChoice of model: Minimal or opt-in
Additional models are documented on paid plans.
Retention or training controlsRetention or training controls: Unavailable
Voice or image inputVoice or image input: Unavailable

On a phone

10 undocumented

Undocumented is not the same as absent - it means the publisher does not state it.

Extensions on mobileExtensions on mobile: Unknown
Extension support on mobile is not documented.
Can be the phone defaultCan be the phone default: Unknown
Default-browser capability is not documented.
Biometric lockBiometric lock: Unknown
Biometric locking is not documented.
Offline readingOffline reading: Unknown
Offline reading is not documented.
Desktop-site modeDesktop-site mode: Unknown
Desktop-site mode is not documented.
Download managerDownload manager: Unknown
A built-in download manager is not documented.
Background playbackBackground playback: Unknown
Background or picture-in-picture playback is not documented.
Web pushWeb push: Unknown
Web push support is not documented.
Data saverData saver: Unknown
Address-bar placementAddress-bar placement: Unknown
Address-bar placement is not documented.

Under the hood

Rendering engine: WebKit
JavaScript engine: JavaScriptCore
Upstream project: WebKit
Release channel: stable
Code and licence: Proprietary browser built on WebKit
Install method: Direct download from the vendor.
Hardware support: Builds target current Apple hardware.

Source repository

Active. Actively developed for macOS with a small team and a freemium model.

Editorial view

SigmaOS asks whether the tab is the right abstraction at all. Instead of a horizontal strip of pages, it organises work into workspaces containing items that behave like tasks, marked done as you finish them. The interface is keyboard-driven, and the learning curve is real: this is not a browser you use efficiently on day one.

The unusual combination

macOS-first and built on WebKit rather than Chromium, which distinguishes it from most workflow browsers. The vendor lists Windows and iOS as coming soon, which is intent rather than shipped software, so both read as unavailable. That platform concentration is the main practical constraint: a workflow browser that exists on one operating system cannot be your workflow everywhere.

The WebKit consequence

Some Chromium extensions are claimed to work, recorded as partial support, but a WebKit browser running Chromium extensions is a compatibility surface that will not be uniform. Test any extension you depend on before committing rather than assuming Chrome behaviour. That is a different level of assurance from any Chromium-based alternative.

Where it earns its place

Workspaces as the organising concept, with pages nesting into subpages
Split view, and a sidebar in place of the tab strip
Lazy Search and a commands filter as keyboard entry points
The Airis assistant with web-answer lookups, in-page rewriting, and additional models on paid plans

The privacy record

Partly documented, partly not. SigmaOS states what it collects, account details and engagement events, and says web activity stays local unless you consent, a clearer position than most workflow browsers take. It cites WebKit's Intelligent Tracking Prevention, its Private Workspace stores no history and clears its own cookies, and cloud sync ships off by default and encrypted. Fingerprinting resistance is undocumented, and the ad-blocking default is recorded as unknown because the pricing page and the documentation disagree.

The verdict

A specialised tool with a real idea and meaningful constraints. If you work on a Mac, live in the browser, and have found tab strips inadequate for years, it rewards the learning investment. If you need cross-platform continuity or specific extensions, the constraints bite before the benefits arrive. Arc's model and Vivaldi's workspaces cover adjacent ground with broader platform support.

Where these facts come from

Every capability above is read from a primary source and dated. 5 of 30 fields stay recorded as unknown rather than assumed.

SigmaOS official site
Product scope, platform availability, and workspace model.
Verified Sep 2026

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