Firefox is adding another AI model to its browser as Mozilla partners with Mistral to bring Mistral Small 4 to the Smart Window beta.

The partnership, announced September 16, expands the AI options available inside Firefox while giving Smart Window users in the U.S. and Canada access to Mistral Small 4. Mozilla is also expanding the beta to France with official French-language support, marking the first expansion of Smart Window beyond North America.

Smart Window is Mozilla’s more deeply integrated AI browsing experience. Rather than functioning as a standalone chatbot, it is designed to work with the context of a user’s browsing session. It can help make sense of complicated searches, compare information across open tabs, find something the user previously clicked away from, and organize related tabs.

Mozilla has also added features such as visual history previews and web sourcing through a partnership with Exa, allowing Smart Window to surface current information while showing the sources behind its responses.

With the new partnership, Mistral Small 4 becomes another model available within that experience. Mozilla says it selected the model after evaluating its performance in Smart Window, with multilingual capabilities playing an important role in the decision.

That is particularly relevant as Mozilla expands Smart Window into France. The company says it and Mistral approached multilingual and multicultural tuning as a core part of the model experience rather than simply adapting an English-first product for another market. France is the first new Smart Window market with official French-language support, while Mozilla says additional European expansion is planned later this year.

The partnership does not mean Mistral is becoming the only AI option in Firefox. Mozilla says users can continue choosing among multiple AI models in markets where Smart Window is available. The companies are presenting that model flexibility as an important part of the collaboration, rather than locking Firefox users into a single AI provider.

Privacy is another part of the pitch. Mistral says conversations in Smart Window aren’t saved on Mozilla’s servers by default, while its agreement with Mozilla includes zero data retention. The companies say the arrangement is intended to combine Firefox’s emphasis on user control and privacy with Mistral’s open-weight AI models.

For Mozilla, the partnership also represents a broader strategy for how AI should fit into the browser. The company argues that the growing integration of AI into web browsers could result in a small number of companies controlling the browser, search engine, AI model, and surrounding services. Its alternative is to keep the browser open to multiple AI providers.

Mistral gets a significant consumer distribution channel in return. While the company has traditionally focused heavily on enterprise AI, bringing its models into Firefox puts Mistral technology directly in front of the browser’s consumer audience. Mistral says Smart Window will initially use its models in France and North America, with the U.K. and Germany expected to follow later this year.

The addition of Mistral Small 4 also comes as Firefox continues experimenting with different levels of AI integration. Smart Window remains a beta feature and is currently available on desktop. Mozilla says users can use it when they want AI assistance across a more involved browsing task and return to a regular Firefox window when they are finished.

For Firefox users, the immediate takeaway is fairly simple: Smart Window is gaining another AI model, while Mozilla is simultaneously expanding the feature into a new language and market. The longer-term significance is the model-selection approach Mozilla is taking—using the browser as a place where multiple AI providers can compete rather than making a single model the permanent foundation of the experience.