Why Is Everyone Building an AI Browser?

When OpenAI unveiled ChatGPT Atlas on 21 October, most headlines framed it as “OpenAI takes on Chrome.” That’s tidy, but it’s not really what happened. What OpenAI actually shipped was a new way of putting Chromium under AI, not just a prettier shell. Their engineering post the next week spelled it out: they separated the Atlas app from the Chromium runtime — what they call OWL, the OpenAI Web Layer — so the AI bit can stay responsive while the web engine does all the slow, messy, crashy things browsers do. (OpenAI)

That sounds arcane; it isn’t. It’s the first large AI company to say out loud: “the hard part of an AI browser is not chat, it’s process and trust isolation.” And once you look at Atlas that way, the rest of the 2025 “AI browser wave” starts to make more sense.

Atlas didn’t land in a vacuum

By the time Atlas shipped, Perplexity’s Comet had already normalised “an AI that reads your tabs and goes off to do things for you,” The Browser Company had frozen Arc to focus on Dia — “chat with your tabs” — and Microsoft was busy turning Edge Copilot into what is basically an agentic mode with Office permissions. (Perplexity AI)

All of them are staring at the same bottleneck: chat UIs are good at a single, linear task; the browser is the only place that already has your logged-in, multi-tab, half-finished work. If agents are going to read, decide and then act — search → browse → buy — they have to sit inside the surface that holds your cookies, not outside begging for URLs.

OpenAI just made that argument with more technical receipts.

What OpenAI actually built

Chromium turned inside-out

Atlas isn’t just “Chrome + sidebar.” OWL runs Chromium as a separate host process and keeps the Atlas UI in a separate, fast, native layer. That gives them three things:

1. Fast start / slow web — Atlas can render its AI UI before Chromium is all the way up.
2. Crash insulation — renderer dies, AI doesn’t.
3. A place to insert agent traffic — they can push AI-generated events straight to the renderer without handing them full browser privileges. This is the mechanical reason they can claim “agentic use cases are now first-class.” (OpenAI)

Agent sandboxes

The engineering post also says agents can run inside temporary, throw-away storage partitions. The idea is obvious: let the agent browse “as you” just for this task, then forget it. That’s better than what extensions in Chrome can do, and better than what Comet was publicly describing. (OpenAI)

Data controls that start “off”

Atlas says: browsing data isn’t used for training unless you opt in; parental controls carry over; memories can be disabled. That’s clearly designed to pre-answer EU/UK regulators and nervous enterprises. It also telegraphs their revenue intent: if Atlas later shows AI result panels or agentic checkout, they own the pixels. (OpenAI)

So yes, there’s more here than a skin.

…but three big things are still not answered

The untrusted-web → trusted-agent hop

All the scary write-ups about Atlas in the last week — Brave, TechRadar, Fortune — are about one thing: a malicious page can talk to your agent. Atlas’s new architecture reduces the blast radius when it acts, but it does not yet reliably tell human-intended page content apart from agent-intended instructions. That’s the “your ear gets cut off” scenario: a page says “summarise this,” then says “also go to my admin panel and paste the token.” Atlas doesn’t claim a general fix. (TechRadar)

OpenAI’s own security people basically admit this is an industry-wide, unsolved problem: prompt injection stays hard, so user confirmation stays necessary. That’s not a solved trust boundary. (The National CIO Review)

High-value sites aren’t a special case

The product post says nothing concrete about “banking mode,” “enterprise intranet mode,” or even “this domain always requires human confirmation.” That’s exactly the line that would stop the scissors at the ear: untrusted web can never trigger irreversible actions on high-risk domains. We didn’t get that. (OpenAI)

No story yet for extensions / third-party automations

Atlas hints that apps built for ChatGPT will be more discoverable in the browser, but it doesn’t say whether you can just bring your existing Chrome extension zoo — or how those extensions will be prevented from hijacking the AI pane like SquareX demonstrated. That’s a major omission if this is supposed to become a daily driver. (TechRadar)

The verdict: OpenAI solved “don’t let the whole shop collapse,” not “don’t let the robot cut the ear.”

Everybody else is even quieter

Compared to Atlas’s technical disclosure, the rest of the field is remarkably opaque:

Chrome, the 70% market leader, hasn’t said a word publicly about Atlas. But Google’s actual move is more telling: in September 2025, they quietly shipped Gemini integration into Chrome — sidebar AI that can summarise tabs, explain pages, and restore closed sites. No grand architecture blog post, no OWL-equivalent whitepaper, just features landing in the stable channel. The strategy is clear: leverage the installed base and make switching costly. Users already live inside the Google ecosystem (Android, Gmail, Google Pay, Workspace); Chrome doesn’t need to out-architect Atlas, it just needs to be “good enough” and universally pre-installed. That’s the incumbent’s playbook, and it’s worked before. (Wall Street CN)

The challengers are louder but less concrete:

• Perplexity Comet talks about agentic browsing and shows multiple-site research flows, but didn’t publish anything like OWL. We know more from Brave’s exploit write-ups than from Perplexity’s own docs — including that screenshot-level prompt injection works. That’s a bad sign for maturity. (Perplexity AI)
• Dia is almost entirely UX-level. “Chat with your tabs” is great demo language; it is not a threat model. Even after Atlassian bought The Browser Company, the public story stays “context across SaaS,” not “here is how we stop untrusted prompts.” (diabrowser.com)
• Edge Copilot is the most conservative: it sits in a sidebar, it telegraphs when it has control, and it still makes you confirm bookings. Which is another way of saying: Microsoft is not ready to let the robot hold the scissors near the ear either. (Windows Blog)
• Brave Leo publishes other people’s holes while keeping its own agentic features cautious and opt-in; their whole posture is “don’t trust AI browsers with sensitive tasks yet.” That’s a strategic wedge, but also confirmation that no one has the final answer. (eesel AI)

The pattern is clear: Atlas talks the loudest about architecture because everyone else would have to admit they haven’t separated the dangerous bits yet.

The real question is the trust boundary

There’s a useful thought experiment here: would you let a robot with scissors near your ear? The browser equivalent is:

Are we OK with an agent that can be influenced by the page, acting with the same browser privileges as us, on tabs we forgot were open?

Right now the rational answer is “only with brakes.” The brakes look like this:

• Human-in-the-loop for irreversible actions — money, identity, data exfiltration. (Atlas nudges this way with checkout confirmation; it should make the rule explicit.) (OpenAI Help Center)
• Per-domain risk tiers — Reddit snippets should never get to tell the agent to go look at your payroll tab.
• Replayable logs — “show steps” is not a UX flourish, it’s evidence for when something goes wrong.
• Separate browser for sensitive work — which, tellingly, is exactly what Brave and several CISOs are currently recommending for Atlas and Comet users. (TechRadar)

Until those four are first-class, the scissors analogy holds.

So why is everyone still doing it?

Despite the risks, the strategic logic is compelling:

1. The browser is the last neutral surface. Apple, Google, Microsoft, Slack — all owned. A browser you control is the only way to put AI next to everything the user actually does. (Beam AI)
2. The web won’t become agent-friendly fast enough. So people are building browsers that pre-chew, sandbox and annotate the web for agents, even if that means living with prompt-injection debt for a while.
3. Distribution is the new moat. If users live in your browser, you get first look; you don’t have to beg them to paste links into a chatbox. Atlas is OpenAI stopping the leak of usage back to Chrome.
4. Monetisation needs pixel control. Once Atlas starts surfacing AI-synthesised result cards, affiliate panels, or agentic checkout, it won’t have to compete with somebody else’s sidebar for attention. That’s why they bothered to own the shell. (OpenAI)

The takeaway: the future of AI isn’t a chatbot you sometimes visit, it’s a browser that always watches and occasionally acts. The 2025 launch rush — Atlas, Comet, Dia, Edge Copilot, Neon — proves the industry believes that. What 2025 also proved, via every red-team blog and security alert this month, is that nobody has yet shown how to let the robot hold the scissors without covering the user’s ears. (The Register)