Firefox just made a quiet but pretty telling move this week – it’s teaming up with Exa.ai, a search and retrieval startup built specifically for the AI era, to power the answer engine behind its new Smart Window feature. If you haven’t been following along, Mozilla has been experimenting with AI inside Firefox for a while now, and this partnership is the clearest signal yet of what kind of AI browser it actually wants to build.

Here’s the thing that makes this announcement different from the usual “we added AI to our product” press release: Mozilla is explicitly positioning itself against the industry trend of one company owning the browser, the search engine, and the AI model all at once. Ajit Varma, who heads up Firefox, put it pretty bluntly – AI shouldn’t be an all-or-nothing offering, and users should be able to pick whatever model or system actually works for them, rather than getting locked into whatever stack a single company decided to build. That’s a not-so-subtle jab at the Google/Chrome/Gemini setup, or really any browser-maker that’s vertically integrating everything from search to the model itself.

So instead of building its own closed AI stack from scratch, Firefox is doing what it’s arguably always done best: partnering with specialists who share its values around privacy and user choice, then wiring those pieces into the browser.

Exa isn’t a household name yet, but in AI circles it’s become a pretty big deal fast. The company builds what it calls a search engine for AI agents rather than humans typing queries into a box, and it already powers retrieval for tools like Cursor and Cognition. It’s grown quickly too – Exa raised $22 million in a seed and Series A round back in mid-2024, then an $85 million Series B in September 2025 at a $700 million valuation led by Benchmark, and just this past May closed a $250 million Series C at a $2.2 billion valuation led by Andreessen Horowitz. That kind of valuation jump in under two years tells you how much money is chasing the idea that AI needs its own kind of search infrastructure, separate from the traditional Google-style web index.

Will Bryk, Exa’s co-founder and CEO, framed the partnership as a natural fit given both companies are trying to avoid the “one company owns everything” trap – he called Firefox “one of the last browsers that isn’t trying to own the model, the search, and the browser all at once.“

Where you’ll actually see this

The practical upshot is that Exa will power two specific features: Smart Window on desktop and Quick Answers on iOS. Smart Window itself has been in beta since around April 2026, rolling out first to users in the US and Canada, and it’s essentially a whole new type of browsing window – sitting alongside Firefox’s Classic and Private modes – that comes with a built-in AI assistant that can actually see your open tabs, browsing history, and whatever page you’re on. It can summarize dense articles, compare information across tabs, answer questions, and help you make sense of a browsing session that’s spiraled into 40 open tabs, which, let’s be honest, happens to all of us.

What’s notable is that Smart Window already gives you a choice of underlying models – options have included gemini-flash-lite, Qwen3, gpt-oss-120B, or even a custom local LLM you run yourself. Exa’s role here isn’t to replace those models; it’s to handle the retrieval layer, meaning it fetches and surfaces the actual source material an answer is based on, rather than having the AI just generate a response and hope it’s right.

The transparency angle

The part of this announcement that Mozilla leans on hardest is citations. When Smart Window gives you an answer, the source is supposed to sit right there in view rather than being tucked away in some separate menu you have to dig for. It sounds like a small UI decision, but it’s really a philosophical one – it’s the difference between an AI that just tells you something and one that shows its work so you can decide whether to trust it. Mozilla is also committing to zero data retention for these AI interactions, which fits the privacy-first branding Firefox has leaned on for two decades now.

Whether this actually moves the needle on Firefox’s market share is a separate question entirely – Firefox has been losing ground to Chrome and Edge for years. But it’s a coherent bet on a different vision of what an “AI browser” should be, and Exa isn’t likely to be the last partner Mozilla brings in this way. The company’s already said as much: expect more partnerships built on the same idea, finding specialists who think AI in a browser should serve the user first, not lock them into a single ecosystem.