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.
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
- 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 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
At a glance
Yab and Firefox, side by side.
| What | Yab | Firefox |
|---|---|---|
| Made by | Serafim Korablev | Mozilla |
| Status | Updated | Updated |
| Runs on | Mac | Mac, Windows, Linux, iPhone and Android |
| Phone app | Not yet | iPhone, iPad and Android; syncs tabs, bookmarks, passwords and history |
| Price | Free; its AI runs on your own Claude or ChatGPT plan | Free; its built-in VPN is free up to 50 GB a month |
| AI | An agent that works in pages, on your Claude or ChatGPT plan | Chat about pages, on its own AI or yours |
| Driven by outside agents | MCP and a command line | MCP |
| Engine | WebKit | Gecko |
| Tabs down the side | Yes | A setting |
| Spaces | Yes | No |
| Split View | Yes | Yes |
| Extensions | Chrome Web Store | Firefox add-ons |
| Ad blocker | Built in | No |
| Open source | No | Yes |
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. 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 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. Firefox can be driven over MCP, through Mozilla’s Firefox DevTools MCP, which starts its own Firefox.
Tabs and windowsYab leads
Yab has tabs down the side, 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
Yab: Free; its AI runs on your own Claude or ChatGPT plan. Firefox: Free; its built-in VPN is free up to 50 GB a month.
Where it runsFirefox leads
Yab runs on Mac. Firefox runs on Mac, Windows, Linux, iPhone and Android. On a Mac, Yab needs macOS 15.4 or later and Firefox needs macOS 10.15 or later. Yab has no phone app yet. On the phone, Firefox: iPhone, iPad and Android; syncs tabs, bookmarks, passwords and history.
Engine and extensionsa matter of taste
Yab is built on WebKit, the engine Safari uses; Firefox on Gecko, Firefox’s engine. Yab takes extensions from the Chrome Web Store, Firefox from Firefox’s add-ons.
PrivacyFirefox leads
Yab has 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. 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.
Where Firefox is better
Firefox comes out ahead on price, where it runs, privacy. It is also the better pick if you:
- Want an open-source browser that isn’t Chromium
- Want AI off by default, or gone with one switch
- Want a free browser VPN, where it is offered
The catch with each
Real limits, from the makers’ own words and our own use.
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 25, 2026Yab: First release
- September 16, 2026Firefox: Smart Window beta expanded from the US and Canada to France
- 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
Moving from Firefox to Yab
Yab takes Firefox’s bookmarks from an exported HTML file and its passwords from a CSV file. It reads Firefox’s files on your Mac; nothing goes through a server, and Firefox stays as it was.
Questions
Is Yab free?
Yes. Free; its AI runs on your own Claude or ChatGPT plan.
Is Firefox free?
Yes. Free; its built-in VPN is free up to 50 GB a month.
Which has an AI agent, Yab or Firefox?
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. 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.
Which runs on Windows, Yab or Firefox?
Firefox does. Yab runs on Mac.
Do Yab and Firefox have phone apps?
Firefox does. Yab has no phone app yet. On the phone, Firefox: iPhone, iPad and Android; syncs tabs, bookmarks, passwords and history.
Can I move from Firefox to Yab?
Yes. Yab takes Firefox’s bookmarks from an exported HTML file and its passwords from a CSV file.
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
- Mozilla blog: Smart Window
- Mozilla Support: get started with Smart Window
- Mozilla Support: model choices in Smart Window
- Smart Window privacy notice
- Firefox.com: Smart Window
- Mozilla blog: window types (2026-09-24)
- Mozilla blog: AI on your terms (AI controls)
- Firefox 148 release notes
- Firefox 149 release notes (split view, VPN)
- Mozilla blog: free built-in VPN
- Firefox 136 release notes (vertical tabs)
- Firefox 138 release notes (tab groups)
- Bugzilla 1730066: tab unloading enabled on macOS (Firefox 95)
- Firefox system requirements
- Firefox ESR 115 release notes (import sources)
- Firefox DevTools MCP (Mozilla)
- Firefox.com: Firefox browser sync
- Firefox on the App Store (iPhone and iPad)
- Firefox on Google Play
- Mozilla Support: Sync Firefox data
Yab, Yet Another Browser.
Free for the Mac. Arc’s sidebar, your own Claude or ChatGPT as the agent, Chrome extensions on WebKit.