Mozilla adds Mistral Small 4 to Firefox Smart Window

Mistral AI and Mozilla have announced a partnership to bring Mistral models to Firefox Smart Window, bringing the French developer’s technology into Mozilla’s AI-focused desktop browsing beta. Mozilla says Mistral Small 4 is being added for Smart Window users in the United States and Canada as the beta rolls out in France.

France is Smart Window’s first market outside North America and receives official French-language support. Mistral will not be the sole model available: Mozilla’s model guide lists three selectable options and lets users switch models or connect a custom endpoint.

Smart Window is an optional desktop beta that requires a Mozilla account. Its assistant can summarize or compare pages, use browsing context selected by the user, retrieve previously visited pages and help organize tabs. Mozilla lists Mistral Small 4 as the “Personalized” option and says Mistral hosts the model.

The model choice does not mean all processing occurs on a user’s computer. Under Mozilla’s privacy notice, a prompt sent to one of Mozilla’s provided endpoints may include the user’s query, relevant Memories and browsing context. Mozilla says it forwards that prompt to the selected model provider, which sees Mozilla’s IP address instead of the user’s. Memories can be created from eligible interactions and browsing activity, may be processed on Mozilla servers, and are returned to and stored on the device. Users can review, delete or disable them.

Mozilla says it does not retain chat logs without permission. Its model documentation says providers do not store conversations and models are not trained on Smart Window data. Those are company and partner policies; the available evidence does not include an independent privacy audit.

The companies also frame the agreement as supporting openness, competition and culturally aware localization. Mistral released Mistral Small 4 under the Apache 2.0 license, establishing the narrower claim that the model is openly licensed. DataPhoenix has previously covered Mistral’s Arabic-language model collaboration with HUMAIN, context for the company’s regional-language work. The partners did not publish independent localization benchmarks, model evaluation scores or data measuring the deal’s effect on browser competition. The concrete localization result announced here is French-language support in France.

A Mozilla implementation record shows the Mistral Small 4 model-selection change was verified in Firefox Nightly 154 on July 14, before the partnership announcement. Mistral says the United Kingdom and Germany are planned to follow later in 2026, but the available sources do not establish that either rollout is live.