I spent five days running Dia as my default browser, mostly because OpenAI confirmed it’s shutting down Atlas and I wanted to know whether the entire AI browser category was cooked or just that one product. Dia is The Browser Company’s follow-up to Arc, now living under Atlassian after the $610M acquisition last September. And the short version of this Dia AI browser review is that the AI is good, the browser is a bill, and the two are stapled together for reasons that have nothing to do with me.

The chat panel is legitimately the best part

Hit Cmd+E and a sidebar slides out that already knows what tab you’re looking at. Ask it to summarize, it summarizes. Point it at six open tabs and ask which vendor’s refund window is shortest, and it reads all six without a single copy-paste.

That’s the whole magic trick, and it works. Every chat window sitting in its own separate tab fails at this, because the model over there has no idea what’s on your screen. Dia’s Skills feature (saved prompt shortcuts you invoke by name) is also better than it sounds. I built one that turns any pricing page into a three-line comparison, and I used it maybe forty times in a week.

So the product thesis is correct. Context beats intelligence. A mediocre model that can see your tab beats a frontier model that can’t.

Then you have to actually move in

Here is what nobody puts in the launch video. Downloading Dia is not installing an app, it’s relocating. You start with an empty profile, which means you are logged into nothing, and every service you touch for the next two days greets you like a stranger asking for a 2FA code. Gmail, then the work Google account, then Slack, then Notion, then the AWS console with its own SSO dance, then Linear, then the two internal admin tools that only your VPN can reach and that your IT team configured against a Chrome profile you no longer use. Password managers help with roughly half of it. The other half is the stuff that lives in cookies nobody thinks about until they’re gone: the session on the invoicing portal, the “remember this device” flag on your bank, the seven-year-old forum account whose password you never actually knew.

Extensions are worse. Dia is Chromium-based so a lot of them technically install, but the ones that mattered to me were the ones that didn’t come cleanly: the screen recorder tied to a desktop helper, the enterprise SSO extension my company pushes by policy, the grammar tool with a device-bound license. And bookmarks import fine while none of the muscle memory does, so for a week I kept opening the wrong browser and then closing it and then opening Dia, feeling stupid each time.

I like Dia’s sidebar a lot. I did not like paying my entire logged-in life for it.

The dia ai browser bet was always fragile

Atlas died in under a year. Arc got shelved by its own maker. The pattern is not that these are bad browsers, it’s that browser switching costs are enormous and an AI feature is not enormous enough to cover them.

Or you keep Chrome and add the panel

The bit that annoys me is that the sidebar doesn’t need the browser. A side panel extension in the Chrome you already use gets exactly the same page context, the same multi-tab reading, the same “summarize this before I read it” behavior, and it gets all of that while you’re already signed into everything. Zero migration. No new profile. Your ad blocker stays where it is.

That’s what we built dassi to be. It sits in Chrome’s side panel, reads whatever you’re looking at, and acts inside your existing session, so the invoicing portal you’re logged into stays logged in. You can sign in with your ChatGPT subscription or drop in your own Claude, Gemini, or DeepSeek key, which also means you pick the model instead of inheriting whichever one the browser vendor negotiated a rate on. It’s free. I wrote something similar about Perplexity’s Comet, and the structural complaint is identical, though Comet asks for more trust than Dia does.

What I’d tell a friend

If you’re a fresh-laptop person with three logins and no extensions, Dia is a pleasant place to live and you should try it. If you have a job, forty tabs, and an SSO policy, the sidebar isn’t worth the move, and the Atlas shutdown is the market telling you the same thing in a louder voice.

The uncomfortable part for The Browser Company is that their best feature is portable and their moat isn’t. Somebody will ship Dia’s sidebar as an extension, and then Dia is just a browser with nice tab management again, which is more or less how Arc ended.