Firefox Smart Window Adds Mistral, Expands to France

Mozilla will add Mistral's Small 4 model to Firefox's Smart Window beta on Sept. 16, 2026, the companies said, extending the AI browsing assistant to France for the first time.

The announcement appeared in matching posts on Mistral's site and Mozilla's Firefox blog. Smart Window is a separate, optional browsing window where a tester asks a chosen AI assistant about open tabs, a page they navigated away from, or a search, instead of typing into the address bar.

Mistral Small 4 joins the beta's model picker

Mistral Small 4 is available immediately to Smart Window testers in the United States, Canada and France, Mozilla said. Mistral agreed to zero data retention on the conversations the model handles, meaning it does not keep them on its own servers, according to both companies' posts.

The United Kingdom and Germany will get the option later in 2026, Mozilla said, without giving a date. France is the first market to get official French-language support inside Smart Window.

What Smart Window offered before Mistral joined

A test build examined by OMG! Ubuntu in March, Firefox 149.0b7 beta, listed three preset providers under Preferences > AI Controls > Smart Window: Google's Gemini Flash Lite, labeled "Fast"; Alibaba Cloud's Qwen3-235B-A22B, labeled "Flexible"; and OpenAI's GPT-OSS 120B, labeled "Personal." That build also let a tester connect a private model by entering its own name, endpoint and API token.

Neither Mozilla nor Mistral said Sept. 16 whether those three presets remain in the current beta or whether Mistral's addition changes the lineup. Mozilla did not say how many testers have joined the Smart Window waitlist at firefox.com/ai.

Where the beta runs, and where it doesn't yet

Market	Status as of Sept. 16, 2026	Language support
United States	Live	English
Canada	Live	English
France	Live	French, new with this rollout
United Kingdom	Planned, later in 2026	English
Germany	Planned, later in 2026	German

Enzor-DeMeo and Mensch frame it as a distribution problem

"A browser shouldn't be a one-way funnel," Mozilla Corporation Chief Executive Anthony Enzor-DeMeo said, adding that the goal is "freedom to explore, discover different ideas and tech." Mistral co-founder and Chief Executive Arthur Mensch said the partnership is about "bringing privacy, control and choice to AI-powered web browsing."

Mistral, which raised €3 billion in a round that valued it above €21 billion in September, is one of the few labs distributing a model directly inside a mainstream browser rather than only through its own chat app. Mozilla's model-picker approach also differs from single-assistant rivals. Google's own Artemis browsing agent is fighting a code-copying dispute with a startup called Minitap, while Firefox lets a tester swap providers entirely or plug in one of their own.

The kill switch stays the default

Smart Window "stays off unless a user turns it on," Decrypt reported in August, describing a separate, existing Mozilla control called Project Nova that disables every AI feature in Firefox at once.

Mozilla said German-language support arrives alongside the U.K. and Germany rollout later in 2026. The company has not set a date for when Smart Window leaves beta.