BrowserOS vs Firefox

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

BrowserOS is an open-source Chromium agent browser for Mac, Windows and Linux. Its agent runs on the AI you connect: an API key, a ChatGPT or Copilot plan, Claude Code or Codex, or a local model.

Firefox is Mozilla’s open-source browser on its own engine, Gecko, on every desktop and phone. Its AI is optional: a Smart Window beta and a sidebar chatbot, all behind one switch.

The short answer

Pick BrowserOS

if you want an open-source agent browser on your own AI keys or local models
if you want Claude Code, Codex or Cursor to drive a signed-in browser over MCP
if you use Linux

Pick Firefox

if you want an open-source browser that isn’t Chromium
if you want AI off by default, or gone with one switch
if you want a free browser VPN, where it is offered

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
if you want Claude Code, Codex or Cursor to drive a real browser over MCP

At a glance

BrowserOS and Firefox, with Yab beside them for a Mac.

BrowserOS vs Firefox
What	BrowserOS	Firefox	Yab
Made by	Felafax, Inc.	Mozilla	Serafim Korablev
Status	Updated	Updated	Updated
Runs on	Mac, Windows and Linux	Mac, Windows, Linux, iPhone and Android	Mac
Phone app	None; desktop only, and no Android plans as of May 2026	iPhone, iPad and Android; syncs tabs, bookmarks, passwords and history	Not yet
Price	Free and open source; you pay your own AI provider	Free; its built-in VPN is free up to 50 GB a month	Free; its AI runs on your own Claude or ChatGPT plan
AI	An agent that works in pages, on its own AI or yours	Chat about pages, on its own AI or yours	An agent that works in pages, on your Claude or ChatGPT plan
Driven by outside agents	MCP and a command line	MCP	MCP and a command line
Engine	Chromium	Gecko	WebKit
Tabs down the side	Yes	A setting	Yes
Spaces	No	No	Yes
Split View	Yes	Yes	Yes
Extensions	Chrome Web Store	Firefox add-ons	Chrome Web Store
Ad blocker	No	No	Built in
Open source	Yes	Yes	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.

AIBrowserOS leads

Only BrowserOS has an agent that clicks, types and finishes tasks in your pages. BrowserOS’s agent, in the new tab and side panel, clicks, types, fills forms and pulls out data, on the AI you connect. Firefox’s Smart Window beta chats with tabs you share and groups them, and a sidebar chatbot can use Claude, ChatGPT, Gemini, Le Chat or Copilot; it can’t click or fill forms, and one switch turns all AI off.

Agents like Claude Code and CodexBrowserOS leads

BrowserOS can be driven over MCP and a command line, through a built-in MCP server with one-click setup for Claude Code, Codex and Cursor, and a command line. Firefox can be driven over MCP, through Mozilla’s Firefox DevTools MCP, which starts its own Firefox.

Tabs and windowsBrowserOS leads

BrowserOS has tabs down the side, Split View and folders in the sidebar. Firefox has tabs down the side as a setting, Split View, folders in the sidebar and tabs that sleep.

Priceeven

BrowserOS: Free and open source; you pay your own AI provider. Firefox: Free; its built-in VPN is free up to 50 GB a month.

Where it runsFirefox leads

BrowserOS runs on Mac, Windows and Linux. Firefox runs on Mac, Windows, Linux, iPhone and Android. On a Mac, Firefox needs macOS 10.15 or later. BrowserOS has no phone app: desktop only, and no Android plans as of May 2026. On the phone, Firefox: iPhone, iPad and Android; syncs tabs, bookmarks, passwords and history.

Engine and extensionsa matter of taste

BrowserOS is built on Chromium, as Chrome is; Firefox on Gecko, Firefox’s engine. BrowserOS takes extensions from the Chrome Web Store, Firefox from Firefox’s add-ons.

PrivacyFirefox leads

BrowserOS has open code. BrowserOS sends prompts and pages only to the AI you connect, or keeps them local with Ollama or LM Studio; it sends anonymous usage analytics. Firefox has a VPN and open code. Smart Window sends prompts and what you share through Mozilla’s servers to partner models; Mozilla says it keeps no chat logs without permission and doesn’t train on them.

What their pages don’t lead with

Real limits, from the makers’ own words and our own use.

BrowserOS

No built-in model since version 0.51: connect a provider before the agent works
Its own docs say local models are too weak for agent tasks
Before 1.0 and changing fast: Skills and Memory were pulled in June 2026
No phone apps

Firefox

Its Smart Window AI is a beta in the US, Canada and France and needs a Mozilla account
Its AI can’t click, fill forms or buy for you
The free VPN covers the browser only, up to 50 GB a month, in a few countries
Firefox add-ons only, not the Chrome Web Store

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 5, 2026BrowserOS: Built-in model and account sign-in removed; Chromium 155 (0.51.0)
September 16, 2026Firefox: Smart Window beta expanded from the US and Canada to France
June 17, 2026BrowserOS: Claude Code and Codex built into the agent; Skills and Memory removed (0.46.0)
March 24, 2026Firefox: Firefox 149 added split view and a free built-in VPN
March 9, 2026BrowserOS: Vertical tabs became the default (0.42.0)
February 24, 2026Firefox: Firefox 148 added AI Controls with a switch that blocks all AI features

Questions

Is BrowserOS free?

Yes. Free and open source; you pay your own AI provider.

Is Firefox free?

Yes. Free; its built-in VPN is free up to 50 GB a month.

Which has an AI agent, BrowserOS or Firefox?

BrowserOS. BrowserOS’s agent, in the new tab and side panel, clicks, types, fills forms and pulls out data, on the AI you connect. Firefox’s Smart Window beta chats with tabs you share and groups them, and a sidebar chatbot can use Claude, ChatGPT, Gemini, Le Chat or Copilot; it can’t click or fill forms, and one switch turns all AI off.

Do BrowserOS and Firefox run on Windows?

Yes, both. BrowserOS runs on Mac, Windows and Linux; Firefox on Mac, Windows, Linux, iPhone and Android.

Do BrowserOS and Firefox have phone apps?

Firefox does. BrowserOS has no phone app: desktop only, and no Android plans as of May 2026. On the phone, Firefox: iPhone, iPad and Android; syncs tabs, bookmarks, passwords and history.

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 BrowserOS; an agent in your signed-in tabs like BrowserOS’s, 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

BrowserOS vs Dia BrowserOS vs Comet BrowserOS vs Atlas BrowserOS vs Opera Neon BrowserOS vs Chrome BrowserOS vs Safari BrowserOS vs Edge BrowserOS alternatives Yab vs BrowserOS Firefox vs Chrome Firefox vs Safari Firefox vs Edge Brave vs Firefox Opera vs Firefox Arc vs Firefox Dia vs Firefox Firefox alternatives Yab vs Firefox

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.

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