In brief

• Mozilla is testing Smart Window, a separate, opt-in Firefox window for chatting with an AI assistant while you browse.
• You pick the model and can turn the whole thing off; Firefox's one-click AI kill switch arrived earlier this year.
• It extends Mozilla's existing sidebar chatbot and leans on "user choice" as the pitch against browsers built by AI companies.

Mozilla is testing a new "Smart Window" in Firefox—a separate, optional window where you can chat with an AI assistant of your choice while you browse. The company is inviting users onto a waitlist to try it first.

The window sits alongside Firefox's Classic and Private modes. You decide when, how, or whether to use AI at all, and you can switch it off if it's not for you. Mozilla's own announcement frames it as "user-controlled," built so you're never locked into one ecosystem or forced into an AI experience. The project is early, and Mozilla says it's building in the open and wants feedback from the first testers.

Mozilla's pitch draws a line with browsers made by AI companies, which it says force a hard choice: use AI all the time or not at all. Firefox, the argument goes, is the independent option that keeps you in control. “In Firefox, you’ll never be locked into one ecosystem or have AI forced into your browsing experience. You decide when, how or whether to use it at all,” Mozilla says.

The Smart Window extends features Mozilla already ships, like the AI chatbot in the sidebar on desktop and Shake to Summarize on iOS.

Browser AI has become a privacy battleground, and the open-source code behind these tools is what lets outside researchers verify their claims.

Brave pushed its own LEO assistant built with Anthropic as a privacy-first alternative, but other companies are building products that sacrifice privacy for convenience. Perplexity Comet, Microsoft Edge, and Opera Neon are among the biggest AI-centric browsers. OpenAI killed its own Atlas browser to focus on the development of a more generalistic app. Google tried enhancing its browser with AI, silently downloading a model that runs locally.

Mozilla is also trying to appeal to a broader user base while keeping its privacy-first roots intact: offer the assistant, but make the off-switch the draw. It ties back to the Project Nova redesign that gave Firefox a single control to disable every AI feature at once.

Mozilla says AI should be “open, accessible, and driven by choice”. The Smart Window waitlist is open at firefox.com/ai, and the feature stays off unless a user turns it on.