Vivaldi vs Firefox

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

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.

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 Vivaldi

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

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

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

Vivaldi vs Firefox
What	Vivaldi	Firefox	Yab
Made by	Vivaldi Technologies	Mozilla	Serafim Korablev
Status	Updated	Updated	Updated
Runs on	Mac, Windows, Linux, iPhone and Android	Mac, Windows, Linux, iPhone and Android	Mac
Phone app	iPhone, iPad and Android; syncs tabs, bookmarks, passwords, history and notes	iPhone, iPad and Android; syncs tabs, bookmarks, passwords and history	Not yet
Price	Free; its Proton VPN is free with a Vivaldi account	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	No AI	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	No	MCP	MCP and a command line
Engine	Chromium	Gecko	WebKit
Tabs down the side	A setting	A setting	Yes
Spaces	Yes	No	Yes
Split View	Yes	Yes	Yes
Extensions	Chrome Web Store	Firefox add-ons	Chrome Web Store
Ad blocker	Built in	No	Built in
Open source	No	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.

AIFirefox leads

Firefox has AI built in; Vivaldi has less of it. Vivaldi has no AI chat, summaries or agents, by choice. 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 CodexFirefox leads

Vivaldi has no MCP server or command line for outside agents. Firefox can be driven over MCP, through Mozilla’s Firefox DevTools MCP, which starts its own Firefox.

Tabs and windowsVivaldi leads

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

PriceFirefox leads

Vivaldi: Free; its Proton VPN is free with a Vivaldi account. Firefox: Free; its built-in VPN is free up to 50 GB a month.

Where it runseven

Both run on Mac, Windows, Linux, iPhone and Android. On a Mac, Vivaldi needs macOS 13 or later and Firefox needs macOS 10.15 or later. On the phone, Vivaldi: iPhone, iPad and Android; syncs tabs, bookmarks, passwords, history and notes. On the phone, Firefox: iPhone, iPad and Android; syncs tabs, bookmarks, passwords and history.

Engine and extensionsa matter of taste

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

Privacyeven

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. 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.

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

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

September 16, 2026Firefox: Smart Window beta expanded from the US and Canada to France
May 21, 2026Vivaldi: Vivaldi 8.0 redesigned the interface
March 24, 2026Firefox: Firefox 149 added split view and a free built-in VPN
February 24, 2026Firefox: Firefox 148 added AI Controls with a switch that blocks all AI features
January 29, 2026Vivaldi: Vivaldi 7.8 restated its no-AI stance
March 27, 2025Vivaldi: Proton VPN built into Vivaldi on desktop

Questions

Is Vivaldi free?

Yes. Free; its Proton VPN is free with a Vivaldi account.

Is Firefox free?

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

Which has an AI agent, Vivaldi or Firefox?

Neither has an agent that does tasks in your pages. Vivaldi has no AI chat, summaries or agents, by choice. 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 Vivaldi and Firefox run on Windows?

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

Do Vivaldi and Firefox have phone apps?

Both do. On the phone, Vivaldi: iPhone, iPad and Android; syncs tabs, bookmarks, passwords, history and notes. On the phone, Firefox: iPhone, iPad and Android; syncs tabs, bookmarks, passwords and history.

Can I move from Vivaldi to Firefox?

Yes: Firefox’s own help says it brings in from Vivaldi.

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 Vivaldi; 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

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

it’s freeMove from Vivaldi Download