Quick answer: Firefox Smart Window is an optional browser window with a built-in AI assistant that can read the page you’re on, your open tabs and your history when you ask it to. Firefox 155, released on 1 September 2026, expanded it to France after earlier launches in the US and Canada. It’s opt-in, needs a Mozilla account, and you can block it (and every other Firefox AI feature) from Settings, then AI Controls.
Mozilla has shipped two Firefox releases in the last five weeks: Firefox 155 on 1 September and Firefox 156 on 15 September 2026. Smart Window is the headline, but there are smaller changes worth knowing about too, including new translation languages for Indian users and a faster PDF viewer.
Here’s what Smart Window actually does, what it can and can’t see, and how to switch it off if you’d rather not have AI in your browser.
What is Firefox Smart Window?
Mozilla describes Smart Window as “an optional window type in Firefox that includes a built-in, AI-powered assistant to help you work with your tabs and browsing history.” It looks and works like a normal Firefox window, with a chat assistant alongside.
You can ask it to summarise the page you’re reading, compare things across several open tabs, or find something you looked at earlier in the week. Firefox 155 added personalised conversation starters, faster answers with web search citations, and better suggestions for organising tabs, according to the official release notes. BetaNews reports that Mozilla says web search citations now come back roughly five times faster than before.
You also get a choice of AI model. OMG! Ubuntu reports that Smart Window offers models from Alibaba, OpenAI and Google, and Mozilla’s help page says you can “choose which model powers the assistant based on what’s important to you.”
Who can use Smart Window?
Not everyone, yet. According to Mozilla’s support page:
- Regions: it began rolling out to users in the US and Canada in Firefox 150, and reached France with Firefox 155. The rollout is gradual, so not everyone in those countries has it yet.
- Account: you need a Mozilla account.
- Device: it’s on Firefox for desktop only, and Mozilla says some parts need “4 GB or more of available RAM” to work as intended.
- Limits: there are daily limits on how much you can chat with the assistant. They reset at midnight US Eastern Time.
If you’re in India or elsewhere outside those three countries, you won’t see Smart Window for now. Mozilla hasn’t announced dates for other regions.
How to open a Smart Window
If it’s available to you, there are two ways in:
- Click the Firefox menu button (three lines, top right) and choose New Smart Window.
- Or, from a normal window, open the menu and select Smart Window to switch the current window over.
Sign in with your Mozilla account when asked, pick a model, and start typing in the assistant panel. You can also stop the assistant sidebar from opening automatically in Smart Window’s settings.
What can the Smart Window assistant see?
This is the part most people care about, and Mozilla is fairly specific. The assistant can access:
- The page you’re currently viewing.
- Open tabs that you reference.
- Browsing history, when you explicitly ask it to look there.
Mozilla says it cannot access activity and data from Private Windows, your saved passwords, payment information, unread emails or files on your device.
On storage, Mozilla says “chat data is not stored by Mozilla or by AI model providers” and that chats are stored locally on your device. That’s a strong claim, and it’s Mozilla’s own description rather than an independent audit. As with any AI assistant, avoid pasting anything into the chat you wouldn’t want processed by a third-party model.
How to turn off AI features in Firefox
Smart Window is opt-in, so nothing changes unless you open one. But if you’d rather not see it, or any other AI feature, Firefox has a single switch for that. Mozilla’s AI Controls guide gives these steps:
- Open the Firefox menu and choose Settings.
- Select AI Controls in the left sidebar.
- Turn on Block AI enhancements.
Mozilla says that with this switch on, “you won’t see new or current AI features in Firefox” and you won’t see pop-ups promoting them either. Future AI features stay blocked by default too.
If you only want to remove Smart Window, go to Settings, then AI Controls, then Smart Window, and select Blocked.
One trade-off to know: the AI Controls panel also covers features some people find genuinely useful, including page translation, AI-generated alt text in PDFs, tab group suggestions, link previews and the chatbot sidebar. The master switch blocks all of them, so you may prefer to block items one by one.
What else is new in Firefox 155 and 156?
Smart Window isn’t the only change. These are the ones most likely to matter to you, from Mozilla’s notes for Firefox 155 and Firefox 156:
- Marathi and Urdu translation (155): Firefox’s built-in page translation now supports both languages.
- Tracker counter (155): the address bar shows how many trackers Firefox has blocked. Mozilla says you can hide the count in settings without turning off tracker blocking.
- Reorder Containers (155): if you use Firefox Containers to separate work and personal browsing, you can now drag them into your preferred order in Settings.
- Game controllers (155): Nintendo Switch Pro controllers now work properly in web games on Windows.
- Faster PDFs (156): the built-in PDF viewer opens up to 45% faster.
- Open at startup on Mac (156): Firefox can now launch automatically when your Mac starts, from the Startup section of Settings.
On Windows and Mac you can update from inside the browser. To check, open the menu, go to Help, then About Firefox. If a site misbehaves after an update, clearing the cache often fixes it; our guide on how to clear your browser cache covers Firefox step by step. For more browser news, see our Apps and Software section.
Frequently asked questions
Is Firefox Smart Window free?
Mozilla’s support page doesn’t list a price, and it’s included in Firefox for eligible users with a Mozilla account. There are daily usage limits on the assistant, which reset at midnight US Eastern Time.
Is Smart Window available in India?
Not as of early October 2026. Mozilla says it’s rolling out gradually, starting with the US and Canada and then France. It hasn’t announced other countries.
Does Firefox turn on AI features without asking?
Smart Window is opt-in, so you have to open one yourself. Other AI-powered features, like translations, can appear in the browser, but the Block AI enhancements switch in Settings hides all of them along with promotional pop-ups.
Can Smart Window see my passwords or private browsing?
Mozilla says no. Its support page states the assistant can’t access Private Windows, passwords, payment information, unread emails or files on your device.