Comet vs ChatGPT Atlas vs Dia: AI Browsers Tested 2026

I asked four browsers to book a dentist appointment. One of them did.

The others got close in ways that were almost more interesting than failure. Perplexity's Comet found the practice, opened the booking widget, picked a slot, and then stopped at a form field asking for my insurance member ID, which it politely asked me to type myself. ChatGPT Atlas got the whole way through on a second attempt after misreading a calendar on the first. Dia, which never claimed it would do this sort of thing, told me which slots were open and handed the clicking back to me. Edge in Copilot Mode opened three tabs of the wrong practice, a place with a similar name forty miles away, and then asked if I wanted a summary of their reviews.

That errand is a fair picture of where AI browsers are in late 2026. The reading and summarising is mature. The doing is real. It is also slower than doing the thing yourself, far more often than the launch videos would have you believe.

If what you want is a better search engine, start with our AI search engine comparison instead. This page is about browsers that act on pages for you, the category our roundup of AI agents touched on before most of these existed.

How I tested

Six weeks, each browser as my default for at least nine working days, rotated so no single one got the easy weeks.

I kept a list of errands and gave every browser the same ones in plain English: rebook a cancelled flight within a fare difference I set, fill a supplier onboarding form from a PDF sitting in another tab, build a comparison spreadsheet of five project management tools from their pricing pages, unsubscribe from everything in a promotions folder older than ninety days, and the dentist. Plus the boring daily stuff. Summarise this 40-page report. What did this Slack thread decide. Find the email where Dana mentioned the invoice number.

I scored an errand as finished only if I did not touch the keyboard between the first prompt and the result, apart from approving a step the browser explicitly asked me to approve. Logins I had already saved did not count against anyone.

The short answer

	Comet	ChatGPT Atlas	Dia	Edge Copilot Mode
Made by	Perplexity	OpenAI	The Browser Company (Atlassian)	Microsoft
Engine	Chromium	Chromium	Chromium	Chromium
Agent errands finished (of 5)	3	4	0 (not really attempted)	1
Best at	Research with sources you can check	Multi-step tasks across sites	Asking questions about your open tabs	Staying inside a Microsoft 365 workday
Weak spot	Stalls on forms that want personal data	Slow, and memory needs pruning	Barely acts on pages at all	Agent sends you to the wrong place
Platforms at test time	macOS, Windows, mobile	macOS first, Windows later	macOS, Windows	Windows, macOS

Atlas finished the most. Comet was the one I trusted most, because it showed its work. Dia was the one I kept open after the test ended.

ChatGPT Atlas: the one that finishes

Atlas is ChatGPT wearing a browser, and that turns out to matter more than any single feature. The sidebar already knows the conversations you have had with ChatGPT, and when you switch on agent mode it takes over the page with a visible cursor and narrates what it is doing in the sidebar while it clicks.

It rebooked the flight. It had to try twice, because the airline's seat map loaded late and the agent read an empty grid as "no seats available", but the second run found a seat, stayed inside the fare difference I set, and stopped at the payment confirmation for me to approve. Seven minutes, start to finish. I would have done it in four. I also would have been annoyed for all four, and with Atlas I was answering email in another window.

The supplier form was the most impressive single run of the test. The agent read the PDF, mapped the fields (including a tax ID buried in a footer), filled eleven of twelve fields correctly, and left the twelfth blank with a note saying the PDF had two conflicting bank account numbers and it would not guess. That is exactly the right behaviour.

Browser memories are the feature to think about before turning on. Atlas can remember things about the sites you visit and use them later, which is how it knew my usual airline without being told. It is also how, in week two, it suggested a restaurant "near your office" that was near a client's office I had visited once. You can view and delete memories in settings and turn the feature off per site. I ended up turning it off for anything involving money or health, which felt like the right line.

Agent mode requires a paid ChatGPT plan. The browser itself is free.

Perplexity Comet: the one that shows its sources

Comet is built around Perplexity's answer engine, and its instinct on almost every request is to go and read things, then tell you what it read, with links. For the project management spreadsheet, that instinct was perfect. It opened all five pricing pages, pulled the per-seat prices and the seat minimums, flagged that one vendor hid its enterprise pricing behind a sales form, and gave me a table with a source link on every cell.

Every one of those cells was correct. I checked.

That verifiability is the single best reason to choose Comet, and none of the others came close on it. Atlas and Edge would give me a confident table. Comet gave me a table I could audit in ninety seconds.

Where it fell short was anything involving personal details. The dentist booking stopped at the insurance field. The supplier form stopped at the tax ID. Comet appears to be deliberately cautious about typing sensitive information on your behalf, which I respect and which also meant two of my five errands ended with a request to finish them myself. It did clear the promotions folder, over about twenty minutes of methodical unsubscribing, and it logged every sender it had removed so I could reverse the one it got wrong.

Comet is free to use, with Perplexity's paid tiers adding more capable models and higher agent limits.

Dia: the one I kept

Dia comes from the team that made Arc, and Atlassian bought the company in 2025. It is the least agentic browser here by a wide margin. It will not book your dentist. What it does better than anything else I tested is let you talk to your tabs.

Open a contract, a pricing page, and a competitor's terms of service, then ask which one has the stricter cancellation clause. Dia answers in the address bar, cites which tab each part of the answer came from, and does it fast enough that it becomes a habit within a day. Its skills feature lets you save a prompt you use often (mine was "rewrite this as a two-line Slack update") and trigger it on any page.

I scored it zero of five errands, which is honest and also misses the point. On the daily reading and summarising work, which was most of my actual browser time, Dia was the quickest and the least intrusive of the four. If you want the AI to answer questions and leave the driving to you, it is the best pick.

Edge Copilot Mode: the one for Microsoft shops

Copilot Mode is an optional switch inside regular Edge, which is its main advantage: nothing new to install, and your company's existing Edge policies still apply. It can see across your open tabs, and on a work account the Copilot sidebar reaches into your Microsoft 365 files and email in a way the others cannot touch without extra connectors.

The agent was the weakest of the three that try. The dentist mix-up was not a one-off. It confused two similarly named suppliers on the form errand, and it gave up on the flight after the airline asked it to verify it was human. It did finish the spreadsheet, though without Comet's per-cell sources.

For someone whose working day already lives in Outlook and Teams, the integration is worth more than the agent, and IT will find it much easier to approve than a new browser from a startup.

The security setting to change first

Every agentic browser has the same underlying risk. A web page can contain instructions hidden in text you cannot see, and an AI reading that page on your behalf may follow them, which security researchers call prompt injection. Researchers demonstrated working attacks against agentic browsers repeatedly through 2025 and 2026, and all four vendors have added defences since. None of them claims the problem is solved.

So I ran agents in a separate browser profile, logged out of email and banking. Atlas has a logged-out agent mode for exactly this reason. Use it.

Privacy, briefly

All four send the content of the pages you ask about to the vendor's servers for processing. Every browser here except Edge lets you view and clear what the assistant has retained, and each has a way to exclude sites. Edge on a work account follows your organisation's Microsoft data policies, which for many companies is the deciding factor on its own. If your job involves client files or patient records, read your company's policy before installing any of them, and ask before assuming "it's just a browser".

Which should you choose?

Choose ChatGPT Atlas if you want the agent to finish multi-step errands across different sites and you already pay for ChatGPT. Prune its memories.

Choose Comet if your work is mostly research and you need to verify every number before it goes into a deck or a report.

Choose Dia if you mostly read, compare, and summarise, and you would rather click the buttons yourself.

Choose Edge Copilot Mode if your company runs on Microsoft 365 and a new browser would take six months to get through IT.

I run Dia as my default and keep Atlas in a second, logged-out profile for errands. That split cost nothing extra beyond the ChatGPT plan I already had, and it kept the agent well away from my email.

Frequently Asked Questions

What is the best AI browser in 2026?

It depends on the job. In a six-week test, ChatGPT Atlas finished the most multi-step errands (four of five), Perplexity Comet produced the most verifiable research with a source link on every fact, and Dia was the fastest for asking questions about open tabs. Edge Copilot Mode suits companies already on Microsoft 365.

Is Comet better than ChatGPT Atlas?

For research, yes. Comet cites a source for nearly everything it tells you, which makes its answers easy to check. For completing tasks like rebooking a flight or filling a form, Atlas was more reliable in testing, while Comet often stopped and asked the user to enter personal details themselves.

Are AI browsers safe to use?

They carry a specific risk called prompt injection, where hidden text on a web page tries to instruct the AI agent. All major vendors have added defences, but none claims to have solved it. Running agent tasks in a separate profile that is logged out of email and banking greatly reduces the exposure.

Is Dia still being developed after the Atlassian acquisition?

Yes. Atlassian acquired The Browser Company in 2025, and Dia continued to ship updates through 2026. It remains focused on chatting with your open tabs and saved skills rather than on autonomous agent tasks.