Mozilla put Mistral's models behind Firefox Smart Window under zero data retention

Ask ChatGPT Atlas to compare five open pages and it drives the browser to do it. In the dev.to comparison by jamilxt, Atlas, Perplexity's Comet and The Browser Company's Dia share one architecture: the agent acts with your authority, reading open pages, navigating, clicking, scrolling and filling forms through your sessions, cookies and logged-in accounts ^[15]. The author reports that cross-tab synthesis works well today and beats copy-pasting into a chat window ^[18].

The capability and its failure mode come from the same place. A language model in a browser has a single input channel, and everything on the open web flows into it: page text, hidden instructions, comments, PDF content ^[17].

Smart Window takes away the actuator and keeps the channel. No agent mode, no form filling, no clicking on your behalf ^[1]. It also cannot book your flight. It still reads the pages you hand it, and those pages can carry hidden instructions ^[17]; what it cannot do is turn that text into a request signed with your cookies.

The permission surface is per task. Smart Window is opt-in, you choose which tabs and how much history it can see for each task, and Firefox's AI Controls turn it off entirely ^[8]. Conversations are not saved on Mozilla's servers by default ^[6]. Mistral operates under zero data retention for this integration, prompts and responses are not kept, and Mozilla states that it will not sell personal data or use conversations to train models ^[7].

What the scope buys you is three features: answers with sources retrieved in place through a partnership with Exa, suggested tab groups with one-click closing of duplicates, and visual previews of pages from your history ^[2]. Mozilla began the project in November 2025 as AI Window and renamed it after beta feedback showed people using it for everyday browsing ^[10]. One beta user described it as a way to keep track of their train of thought ^[11].

Mistral raised 3 billion euros in September 2026 at a valuation of 21 billion euros, the largest European tech fundraising on record ^[12]. The raise is about one seventh of that valuation ^[20]. The company is still far smaller than OpenAI or Anthropic, and its models are open-weight, so clients can inspect them and run them on their own infrastructure ^[13]. The dev.to author argues that Mozilla, a nonprofit that has spent two decades arguing one company should not control the web, picked the one major lab whose technology it could theoretically audit, and that the pairing is not accidental ^[14].

One caveat on the evidence for the two-camp split. The author writes that he has not used Smart Window and worked from Mozilla's blog posts, the Mistral announcement and security writing on the agentic browser category ^[19]. That record describes commitments and architecture, and it does not cover how either product behaves under a corporate login.

Smart Window is in beta in the United States, Canada and, as of that week, France, with the United Kingdom and Germany expected later this year ^[9][5]. France went live first, in French, the first expansion beyond North America ^[5].