Does Mozilla Firefox train on your data?
Firefox's AI features run on your device, and Mozilla says browsing content is not used for training without your explicit consent. The AI you can turn on is somebody else's.
A self-serve opt-out exists
"These operate locally - web page content, PDFs, images and tab URLs stay on your device and are not sent to Mozilla's servers or used for training purposes without your explicit consent."
- 7 Sept 2026
- 5 Oct 2026
- Firefox (all users)
- global
- Fetched from the company
- 75CCB557…A39C
How we read it: Two commitments do the work, and both are unhedged. Firefox's built-in AI runs on "small language models downloaded to your device", and what those models see — page content, PDFs, images, tab URLs — stays there and is not used for training without explicit consent. The third-party chatbots are separately opt-in, with the legal basis given as "Consent, when you choose to enable an AI chatbot". Nothing starts unless you start it, which is the B. Two bounds, stated rather than left to be found: enable a third-party chatbot and that provider's terms govern, which Mozilla says plainly; and Smart Window has a separate notice this capture does not cover, so it sits outside this grade.
consent, opt out, settings, control, AI
What the document does offer
- "not sent to Mozilla's servers or used for training purposes without your explicit consent" — consent gating the training question directly
- "Consent, when you choose to enable an AI chatbot" — the stated legal basis for the third-party chatbots
- "how to control AI-based features and models in your settings" — the control is named and located in settings
Why none of it applies: Consent is the legal basis for the AI features rather than legitimate interest, which is the difference between this and the D-grade entries elsewhere on the site: there, training runs until you stop it; here it does not start until you begin it.
What each plan can refuse
The same questions, asked of every plan we could identify. Every cell comes from a quoted clause or a documented search - see the evidence above.
- Nothing to switch off
- Not stated
- 18 / 100
- Not stated
- Unknown
How to opt out of Mozilla Firefox AI training
Plan by plan, from what Mozilla Firefox's own policy says about refusing. Where it publishes the steps, they're listed here with the limits they carry. Where there's nothing to switch off, or nothing graded, this says so instead of inventing a menu path.
Firefox (all users)
Nothing to switch off: training here is off until an opt-in is given, in a self-serve setting.
What this policy has done since we started watching
No change detected. We've held a copy of Mozilla Firefox's policy since 30 Aug 2026 and re-read it since, across 2 captures. The text hasn't moved in a way that touches this verdict. That's a fact about the document, and it's only knowable by having kept the earlier copies.
Everything we read
Vendor response
We haven't yet written to Mozilla Firefox about this verdict, and they haven't disputed, clarified or announced a change to any clause quoted above. When either happens it's published here, word for word.
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Mozilla Firefox is graded B, and a company that's earned that can say so with the verdict itself. The image below links back to this page and shows the live grade. If the grade changes, the badge changes the same day, wherever it's embedded. It's free and it isn't for sale.
