Dia Browser Review: The Browser Company After Arc

Dia is what The Browser Company built after Arc — a free, Chromium-based browser that puts an AI assistant at the center of the experience instead of treating it as an add-on. Then, in October 2025, Atlassian bought The Browser Company outright, and Dia (not Arc) became the product Atlassian says it’s building around.

This review sticks to what’s published on Dia’s own homepage and Security page, plus what Arc’s own site now says about itself, since the two are tightly linked. Where a detail isn’t confirmed on an official page, that’s stated plainly rather than guessed at. You’ll get the honest picture on pricing, platforms, privacy, and the Arc-to-Dia transition — plus what to do about your tabs if you’re moving over, since Dia doesn’t cover that risk on its own.

What Is Dia Browser?

Dia is The Browser Company’s AI-first web browser, built on Chromium and offered free of charge. Its own homepage states plainly, “Download Dia for free,” with no separate purchase step or trial gate for the core browser.

The Browser Company is the same team that made Arc, the tab-and-sidebar browser that built a loyal following before its own maker started steering users elsewhere. Dia is the successor product, and the company’s messaging (echoed in Atlassian’s own acquisition announcement) treats it as the answer to “what comes after Arc,” built for “workflows, rather than just browsing.”

Dia arrived into a crowded year for AI-first browsers. Perplexity’s Comet went free worldwide on October 2, 2025; nineteen days later, on October 21, 2025, OpenAI launched ChatGPT Atlas, also Chromium-based, with ChatGPT built into a sidebar. Dia predates both, but the timing means anyone shopping for an AI browser right now is choosing between several young products released within weeks of each other, not picking an obvious category leader.

If you’re coming to Dia from Arc specifically, or comparing it against Perplexity’s Comet, our Arc browser status guide and Comet browser review cover those two products in the same depth as this one.

Quick Answer: Should You Switch to Dia in 2026?

Short version: Dia is worth trying if you’re on a Mac, already use Arc, and want The Browser Company’s newer AI features. It’s riskier if you’re on Windows or need HIPAA-level data handling.

Dia’s pitch is coherent and its Security page is unusually transparent for a browser vendor, which counts for something. What it can’t offer yet is Windows availability or a long track record, so weigh that against how much you need AI features specifically. See our browser comparison hub for how Dia’s confirmed facts stack up against other Chromium browsers feature by feature.

Is Dia Available for Windows?

No, not yet, as of September 2026. Dia’s own homepage lists availability as “Available for macOS · Windows coming soon,” which confirms two things at once: macOS is a fully open download with no waitlist, and Windows has no stated release date.

That’s a meaningful limitation if you split your time between a Mac and a Windows PC, or if your household or team standardizes on Windows. There’s no workaround published by The Browser Company for running Dia on Windows in the meantime — no beta channel, no early-access program mentioned on the page checked for this review.

Mac-only, for now. If Windows support matters to you, it’s worth checking Dia’s homepage periodically rather than assuming the “coming soon” label has an near-term timeline attached. The Browser Company hasn’t published a date as of this review.

If you’re on Windows and want an AI-forward browser you can actually install today, Microsoft’s own Copilot Mode in Edge and OpenAI’s ChatGPT Atlas both had Windows availability at different points in their rollout — our AI browser comparison covers what’s confirmed for each.

What Happened to Arc? Is Dia Its Replacement?

Arc still works, but its own maker is actively pointing users toward Dia instead. Arc’s site tells visitors directly: “Arc receives Chromium updates only. For active security patches and enterprise-grade protection, download Dia instead.” That’s about as clear a signal as a company can give without formally shutting a product down.

The business context explains why. Atlassian completed its acquisition of The Browser Company (maker of both Dia and Arc) on October 21, 2025, in a $610 million all-cash deal. Atlassian’s own announcement frames Dia as the company’s focus going forward, describing it as built for “workflows, rather than just browsing,” which lines up with enterprise-collaboration tools being Atlassian’s core business.

Our full Arc browser status guide goes deeper on what “Chromium updates only” means in practice and how to move your tabs and data out if you decide to switch.

What Are Dia’s Main AI Features?

Dia’s AI centers on three named features that pull context from your day rather than requiring you to ask for it each time. Its own homepage describes them as follows.

• Morning Brief. A daily AI-generated summary pulling from “calendar, inbox, key links,” meant to catch you up before you start working.
• Synthesis. A cross-tool context search described as digging “into your full context, across GSuite, Teams, tabs, and more” — effectively a search layer over everything you’ve touched recently.
• Decks. A feature that converts “scattered context” you’ve gathered into a slide presentation automatically.
• Organized Tabs. A grouping feature for open tabs, paired with “Profiles” that separate tabs, logins, and AI context between settings like work and personal.

Beyond those, Dia’s homepage also names a split-screen view for looking at a document and a meeting at the same time, which is a smaller but practical detail for anyone doing video calls alongside note-taking. Taken together, these features position Dia less as “a browser with an AI chat bolted on” and more as a tool trying to replace the tab-juggling itself.

That ambition puts Dia in similar territory to Google’s Gemini Auto Browse, which handles what Google calls “multi-step chores” (planning trips, filling out forms, managing subscriptions) though Auto Browse is presently limited to a US preview for Google AI Pro and Ultra subscribers. Brave takes a narrower, more privacy-first approach with its Leo assistant, which requires no account and, per Brave’s own claims, doesn’t retain or share chats. Dia sits between those two: more ambitious than Leo’s chat-only scope, but without Google’s stated confirmation prompts before an action like a purchase.

It’s worth being clear-eyed about scope, though. Every feature above comes from Dia’s own marketing copy, not an independent test, and features described in vendor copy don’t always match day-to-day reliability. If AI daily summaries and cross-tool search are the reason you’re considering Dia, they’re also the features most worth trying hands-on before you commit your daily workflow to them.

How Does Dia Handle Privacy and Data?

Dia’s default is local-first storage, according to its own Security page: “Your conversations, history, bookmarks, and files are encrypted and stored locally on your device.” That’s a stronger baseline privacy stance than many browsers state outright.

When you do turn on sync, Dia’s Security page describes it as end-to-end encrypted — sync data passes through Dia’s servers but, in the vendor’s own words, “remains unreadable to them.” Dia also names a specific, opt-out “improvement data” category: it’s not linked to your account, is retained for 30 days and then deleted, and you can disable the collection entirely.

On the business-model question, Dia’s Security page states the vendor “explicitly states data is not sold and browsing data isn’t collected for ad profiling.” Dia’s homepage also surfaces privacy controls directly in its marketing copy rather than burying them in settings: “Block trackers,” “Block ads,” “Personalize new chats Off,” “Memory On/Off,” and “Share content data Off” are all named as visible toggles.

That’s a reasonable case for privacy-conscious users, but it comes from Dia’s own page, not independent verification — the same caveat that applies to any browser vendor’s self-description of its own privacy practices.

Is Dia Safe for Work and Business Use?

Partially, with one hard limit stated by the vendor itself. Dia’s Security page says directly that the product is “not HIPAA-compliant,” is “unsuitable for PHI or legally protected data,” and that no Business Associate Agreement is offered. If your work touches health records or similarly regulated information, that’s a clear no from Dia’s own documentation, not a guess.

Outside of regulated health data, Dia does offer a business-oriented add-on. “Dia for Work” is named on Dia’s homepage as adding “SSO and admin tools” on top of the standard free browser, which suggests The Browser Company is building toward broader enterprise use even while keeping the HIPAA caveat in place.

There’s also an AI-specific caveat worth knowing before you connect Dia to work accounts. Dia’s Security page names the third-party AI providers behind its features (Anthropic, OpenAI, Google, Azure, and AWS) and states they “receive user prompts and page content but are contractually restricted from retention or training use.” That’s Dia’s own framing of how your prompts and page content flow to outside companies, contractually limited rather than technically prevented.

1. Check whether your data is regulated. If you work with PHI or other legally protected data, don’t use Dia for that specific work — its own Security page rules it out.
2. Review the third-party AI provider list. Know that prompts and page content can reach Anthropic, OpenAI, Google, Azure, or AWS under contractual restrictions, per Dia’s own disclosure.
3. Decide if Dia for Work fits your team. If you need SSO and admin controls, that’s a named add-on rather than something in the free tier.
4. Read the prompt-injection caveat. Dia’s Security page describes its own defenses as “layered but imperfect” — treat that as an honest limitation, not a solved problem.

That last point deserves its own attention, since it’s rarer for a vendor to state directly.

For comparison, Microsoft’s own language on Copilot Mode in Edge states “your data stays yours” and that data is “never shared without your permission,” with “clear visual cues” when Copilot takes an action. Google states it has trained Gemini’s Auto Browse to detect prompt injection and designed it to pause for explicit confirmation before purchases or social posts. Dia’s own disclosure is different in kind: it names the specific outside companies involved and admits its defenses are imperfect, rather than promising a fully solved problem. Which approach you trust more is a judgment call, but Dia’s is at least concrete enough to evaluate.

Is Dia Built on Chromium?

Yes. Dia’s own Security page states it is “built on the open-source Chromium engine — the same foundation as Chrome and Edge.” That places Dia in the same lineage as Chrome, Edge, Brave, Opera, Vivaldi, Arc, and Comet — all Chromium-based, all rendering the web roughly the same way underneath their different interfaces.

What sets Dia apart on the Chromium question isn’t the engine itself but how it’s maintained. Dia’s Security page describes inheriting Chromium security patches on “an aggressive upgrade cadence,” naming weekly Thursday releases plus critical fixes delivered within 48 hours. That’s a specific, checkable commitment (not a vague “we keep things updated” claim) and it’s a notably faster cadence than Arc’s own “Chromium updates only” position covered earlier in this review.

If update speed and patch cadence matter to how you evaluate a browser’s security posture, Dia’s stated cadence is one of the more concrete numbers any Chromium-based browser vendor has published this session. Compare that against our coverage of Chrome, Edge, and other Chromium browsers to see how update practices vary across the same underlying engine.

Comet, Perplexity’s own Chromium-based AI browser, hasn’t published an equivalent cadence statement on the pages available for this review, which makes Dia’s specific numbers (weekly Thursday releases, 48-hour critical fixes) stand out even more. A vendor that names its patch schedule is giving you something to hold it to; one that doesn’t isn’t necessarily behind, just less transparent about the number.

Does Dia Support Extensions?

This isn’t confirmed on an official Dia page reachable during this review’s research pass, so the honest answer is: check The Browser Company’s own site before assuming either way. Chromium-based browsers don’t all handle extension-store compatibility the same way — some support the Chrome Web Store directly, some have their own curated stores, and some restrict it entirely.

Orion, a WebKit-based browser from Kagi, shows how differently vendors can approach this even without sharing Dia’s engine: it supports installing extensions from three separate stores (Safari’s, Chrome’s, and Firefox’s) through a curated list of roughly twenty guaranteed-to-work options. That’s a reminder that extension compatibility is a product decision each maker chooses to build, not a side effect of picking Chromium or WebKit as a foundation.

If extensions are a dealbreaker for you (a password manager, an ad blocker, a specific productivity tool you rely on daily) that’s a good reason to confirm compatibility before you make Dia your primary browser. Chrome, Edge, Brave, and Vivaldi all have well-documented, mature extension ecosystems if you need that certainty today.

Given how new Dia is and how quickly The Browser Company has been shipping features (weekly Thursday releases, per its own Security page), it’s plausible extension support gets clarified or expanded soon. Until then, treat it as an open question rather than an assumed yes.

Does BelayTab Work With Dia Browser?

No — as of September 2026, BelayTab does not support Dia. BelayTab currently works on Chrome, Edge, Brave, Opera, Vivaldi, Arc, Firefox, and Safari on Mac, and Dia isn’t on that list. We’d rather say that plainly than let you assume compatibility that isn’t there.

There’s a useful detail here for anyone coming from Arc, though: Arc is on BelayTab’s supported list. If you’re weighing whether to fully commit to Dia or keep a foot in Arc while Dia matures (especially since Arc’s own site still lets you use it, even with reduced update support) you can protect everything in that Arc window today.

BelayTab is free, with no account required and no limits on sessions or tabs, so there’s no real cost to running it in Arc, Chrome, or another supported browser while you evaluate Dia on the side. See how saving works and how recovery works for the full detail, and check the full list of supported browsers to confirm which of your installed browsers qualifies.

It’s worth knowing what BelayTab’s optional paid Sync tier does and doesn’t reach here, too. Sync keeps sessions available across the browsers you sign into and keeps 90 days of cloud version history, but that only applies to browsers BelayTab already supports. It has no way to pull sessions out of Dia, since BelayTab can’t run inside Dia at all yet. Even without Sync, the free tier keeps the last 20 versions of every saved session, so restoring never overwrites what you had; it just adds another version, and anything you delete sits in a 30-day trash first.