Dia (browser)
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Last reviewed
May 16, 2026
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Dia is an AI-first web browser developed by The Browser Company of New York. It was first teased on December 2, 2024, entered private beta on June 11, 2025, and reached general availability on macOS on October 8, 2025. Built on top of Chromium, Dia places a large language model directly into the browser's omnibox and a right-hand sidebar, letting users chat with the contents of their open tabs, run reusable prompt shortcuts called Skills, and have the assistant draft, summarize, or compare information without leaving the page.
Dia is the company's second product after the Arc browser, and its arrival came together with a controversial pivot: in late May 2025 The Browser Company announced that Arc had entered maintenance mode and that all future development would happen on Dia. Three months later, on September 4, 2025, Atlassian agreed to buy The Browser Company for $610 million in cash, citing Dia as the foundation for a new generation of work-focused browsers. The acquisition closed on October 21, 2025. Dia continues to be developed under the leadership of co-founder and CEO Josh Miller, with the team operating as an independent unit inside Atlassian.
Dia competes with Perplexity Comet, ChatGPT Atlas, and Microsoft Edge with Copilot Mode in the small but fast-moving category of AI-native browsers. It is generally considered the less agentic of the bunch, focused on conversation with open content and human-supervised writing rather than fully autonomous web automation.
The Browser Company of New York was founded in 2019 by Josh Miller and Hursh Agrawal. The company was incubated inside the venture firm Thrive Capital, where Miller had been working as an investor after a stint as Director of Product for digital strategy at the Obama White House and after his earlier startup, Branch, was acquired by Facebook in 2014. Thrive's founder Josh Kushner brought the idea to Miller; Miller in turn convinced Agrawal, his Branch co-founder, to leave Tinder to build with him.
The company raised an initial seed round in 2020 with notable backers including LinkedIn CEO Jeff Weiner, Figma CEO Dylan Field, Notion co-founder Akshay Kothari, and former GitHub CTO Jason Warner. A larger Series B led by Pace Capital closed in March 2024 at a $550 million post-money valuation, taking total funding to roughly $128 million across all rounds.
From its founding the company described itself as building "the internet computer," arguing that the browser had stagnated as a category and that there was room for a new kind of operating environment around the web. That thesis produced Arc, then Dia.
Arc, the company's first product, entered private beta in 2021 and launched publicly in 2023. It introduced an unusual set of design choices for a Chromium-based browser, including a left-hand sidebar instead of horizontal tabs, automatic tab archiving, profile and workspace separation via a feature called Spaces, a built-in note and easel scratchpad, and AI features such as Ask on Page and the standalone mobile companion Arc Search. Arc attracted a devoted enthusiast audience and a wave of glowing coverage from tech press in 2023 and 2024, but its adoption never reached the level of a mass-market browser.
In an open letter published on the company's Substack on May 26, 2025, Miller publicly diagnosed the reasons. Arc, he wrote, suffered from a "novelty tax": users who tried it tended to stick, but the learning curve was too steep for most people. Internal data showed that only 5.52 percent of users used multiple Spaces, and that just 0.4 percent used the Calendar Preview on Hover feature, indicating that most of Arc's distinctive ideas reached almost nobody. The product had also been built on Swift, SwiftUI, and The Composable Architecture, which the team considered too heavy and slow for the kind of fast, security-hardened browser they wanted to ship next.
By the summer of 2024, Miller and his co-founders had concluded that AI was not a feature to be bolted onto Arc but a reason to start over. In the May 2025 letter, Miller framed the shift in unusually direct terms: "Electric intelligence is here, and it would be naive of us to pretend it doesn't fundamentally change the kind of product we need to build to meet the moment." He repeated the line in interviews and on his X account, where he has narrated the company's strategy publicly throughout the transition.
The internal decision to spin up Dia as a separate codebase, rather than evolve Arc, was made over the course of 2024. The team scaled up the security engineering group from one to five people for the new browser, and chose to rebuild on top of Chromium with a smaller native shell so that the product could ship on multiple operating systems and pass enterprise security review.
The Browser Company published a short teaser video for Dia on December 2, 2024, calling it the company's next product and framing it as "a new way of using your computer." The teaser showed AI features running inside a browser frame: an inline writing tool inside a Gmail draft, the browser automatically adding several items to an Amazon cart based on a list from an email, and the browser reading a Notion table and sending personalized emails to each row. The clip did not commit to a release date, but Miller said publicly that the team was aiming for an early 2025 launch.
The project missed that target. A semi-private alpha went out to early Arc supporters during the spring of 2025, and the public beta opened on June 11, 2025, initially limited to Arc members and people invited from the existing beta. TechCrunch, 9to5Mac, and Engadget all covered the beta launch the same day. Beta access was restricted to Apple Silicon Macs running macOS 14 Sonoma or later.
Dia exited the waitlist and became generally available on macOS on October 8, 2025. The download moved from invite-only to a public landing page at diabrowser.com, and the company removed the invite gate that had governed access through the summer. As of May 2026 a Windows build is in development but has not shipped; the company maintains a waitlist for it on the official site.
Dia is a Chromium browser with the chrome stripped back and the AI assistant promoted to a first-class component of the interface. The omnibox at the top of every window acts as a unified entry point: typing a URL navigates, typing a query runs a web search, and asking a question opens a chat panel on the right-hand side that has read access to whatever tabs the user grants it. Skills are the customization layer on top of that.
| Feature | Description |
|---|---|
| Chat with your tabs | The AI sidebar can read one tab, several selected tabs, or every tab in a window, and answer questions, compare information, draft summaries, or extract structured data. |
| Omnibox AI | A combined URL bar, search bar, and chat entry point. Plain text goes to web search; a question routes to the model. |
| Skills | User-authored prompt shortcuts written in plain English and triggered with a slash command. Skills can call other Skills and reference open tabs as context. |
| Inline writing | Cursor-level rewrites and continuations inside text fields, comparable to Apple Intelligence Writing Tools but available in any web app. |
| Personalization | Per-user voice, tone, and coding style preferences stored locally and applied to AI output. |
| Optional browsing memory | Seven-day local memory of recently visited pages that the assistant can use as context. Off by default and opt-in. |
| Skills Gallery | Public gallery at diabrowser.com/skills where users can install Skills shared by other users. |
| Vertical tabs and sidebar | Added in late 2025 after the Atlassian deal, alongside grid-view pinned tabs and a Focus mode borrowed from Arc. |
| Picture-in-picture meetings | Google Meet picture-in-picture window for ambient calls, also imported from Arc. |
| Profiles | Separate work and personal contexts, each with its own tabs, history, and signed-in accounts. |
| Splits | Two-pane side-by-side layouts inside a single window. |
| Tracker and ad blocking | On by default, with optional end-to-end encrypted sync. |
Not every Arc feature has been ported. Spaces, the workspace switcher that was central to Arc's identity, was still in testing as of late 2025. The Arc command bar that opened with Cmd+T has been replaced in Dia by the AI omnibox, which behaves differently and produced some friction with Arc loyalists during the transition.
Dia is a Chromium-based browser with a native macOS shell, written from scratch rather than forked from Arc. The team has said publicly that they wrote a new internal SDK to replace the Arc Development Kit, the proprietary framework that powered Arc's custom UI. The new architecture emphasizes startup time, memory footprint, and a tighter security boundary between the browser process and the AI assistant.
The AI sidebar is a separate process that talks to a hosted backend. When the user includes a tab as context, Dia sends the page contents (or a summarized derivative, depending on length) to the model through the company's servers. The Browser Company has said that conversation data is encrypted in transit, kept on its servers "for milliseconds" while a response is generated, and not used to train models. Browsing history used as context is stored locally on the device.
The company has not publicly disclosed which underlying language models power Dia's assistant. Reporting around the launch suggested the product routes between several frontier model providers depending on query type, but the company has declined to confirm specific vendors. Skills run as prompt templates evaluated at request time; they do not execute arbitrary code on the local machine.
Dia inherits Chromium's extension model, so most Chrome extensions install and run. The browser supports passkeys, password import from Chrome and Safari, and the standard set of Chromium developer tools.
The decision to put Arc into maintenance mode was the most contentious moment in The Browser Company's public history. Arc had a loud and loyal user base that spent years promoting the browser through tutorials, screencasts, and word of mouth. Many of those users felt blindsided by the announcement.
Miller's May 26, 2025 letter laid out the reasoning, but it also confirmed that Arc would receive only Chromium engine updates, security patches, and as-needed bug fixes from that point forward. No new features were planned. The post triggered a long debate on Hacker News and a wave of critical posts on X and YouTube. Common complaints included: that paying Arc users had received no warning, that Arc Search on iOS and Android would also be deprioritized, and that the company had not committed to open-sourcing Arc despite the maintenance status. Miller said in the same letter that open-sourcing Arc was on the table but that Arc and the early Dia codebase still shared parts of the proprietary Arc Development Kit, which complicated an immediate release.
The transition coincided with two practical problems for the loudest Arc fans. First, Dia's early builds had fewer power-user features than Arc, including no vertical tabs, no Spaces, and no command bar in the Arc sense. Second, Dia was Apple Silicon only at launch, leaving Arc's Windows audience without a clear migration path. The Browser Company moved on both fronts during the second half of 2025, adding a vertical sidebar, vertical tabs, pinned-tab grid, Focus mode, custom keyboard shortcuts, and Google Meet picture-in-picture in the months following the Atlassian deal.
Miller addressed the criticism repeatedly in interviews, on his X feed, and on the company blog. His consistent message: Arc was the right product for the desktop browser era, Dia is the right product for the AI era, and the company could not afford to do both well.
On September 4, 2025, Atlassian announced a definitive agreement to acquire The Browser Company for $610 million in cash. The Australian software company is best known for Jira, Confluence, Trello, and the Atlassian Intelligence layer it has been building across those products. Atlassian co-founder and co-CEO Mike Cannon-Brookes wrote the announcement post and described Dia as the basis for a browser "reimagined for knowledge work in the AI era," arguing in a quote widely repeated in coverage that "today's browsers weren't built for work, they were built for browsing."
The deal closed on October 21, 2025. The Browser Company became a wholly-owned subsidiary of Atlassian. Josh Miller continued in a leadership role, and the company publicly committed to keeping Dia available as a consumer product rather than restricting it to Atlassian customers. Miller emphasized in interviews that Dia would remain for individual users, although Atlassian's strategic interest was clearly in the enterprise side of the use case.
The acquisition price compared to a prior post-money valuation of $550 million from the March 2024 Series B led by Pace Capital. Total prior funding for The Browser Company stood at around $128 million across seed and Series B rounds, so the deal returned roughly 4.8x of invested capital to backers in cash. Reporting from CNBC, TechCrunch, and Daring Fireball described the price as a modest premium and a structurally clean exit for an unprofitable consumer software company that had not yet found a revenue model.
Atlassian framed the deal around three strategic pillars: a browser optimized for SaaS tabs where most office work happens, an embedded AI layer with skills and persistent work memory, and enterprise security and admin controls in a category where, by Atlassian's own count, fewer than ten percent of organizations had standardized on a secure work browser. Atlassian also began shipping Rovo, its agent platform, into Dia after the acquisition closed.
For the first two months after the public beta, Dia was free with usage limits that the company did not publicly enumerate. On August 6, 2025, The Browser Company introduced Dia Pro, a $20 per month subscription that provides unlimited access to the AI chat and Skills features. Miller told The New York Times that the free tier would remain usable for people who hit the AI a few times a week, and indicated that future paid tiers could range from around $5 a month for light users to several hundred dollars a month for heavy power users. As of May 2026, Dia Pro is the only paid tier publicly available.
Atlassian has not yet rolled Dia into its enterprise pricing book, although Cannon-Brookes hinted in the acquisition post that a business tier with admin controls would arrive over the course of 2026.
Dia, Perplexity Comet, ChatGPT Atlas, and Microsoft Edge with Copilot Mode all ship an AI assistant as part of the core browsing surface, but they make different bets about how aggressive the assistant should be.
| Browser | Released | Built on | Default assistant | Agent autonomy | Primary use case |
|---|---|---|---|---|---|
| Dia | June 2025 beta, October 2025 GA | Chromium | Dia chat with Skills | Low. Reads and writes inside open tabs, no general DOM automation. | Writing, research, and chatting with open tabs. |
| Perplexity Comet | July 2025 | Chromium | Perplexity assistant | Medium. Includes Comet Assistant for multi-step browsing tasks. | Cited research and answer-first browsing. |
| ChatGPT Atlas | October 2025 | Chromium | ChatGPT with Agent Mode | High. Agent Mode can click through sites and complete multi-step tasks. | Power use for ChatGPT subscribers. |
| Microsoft Edge Copilot Mode | 2025 update to Edge | Chromium | Microsoft Copilot | Medium. Tab-aware actions and some workflow agents. | Office and Microsoft 365 integration. |
| Google Chrome with Gemini | Ongoing | Chromium | Gemini in Chrome | Low to medium. Page-level summarization and write assistance. | Mass-market default with light AI. |
Reviewers generally describe Dia as the most polished and least pushy of the AI browsers. It does not try to autopilot through complex web tasks the way Atlas does, and it does not surface a search-engine-style answer pane the way Comet does. Its biggest single advantage is the ability to mix many tabs into a single conversation, which makes it a strong tool for research, comparison shopping, and long-form writing.
Early coverage of the Dia beta was largely positive on craft and skeptical on category. The Verge's David Pierce interviewed Miller around the beta launch and wrote that Dia's ability to reference several tabs at once was its most impressive initial feature, while noting that the browser still felt rough around the edges and was Mac-only. TechCrunch covered both the beta launch and the November 2025 update that ported Arc's most popular features into Dia. 9to5Mac, Engadget, and MacRumors covered the October 2025 general availability launch with similar framing: a working AI browser from a team with a strong design reputation, still incomplete, and now backed by Atlassian's balance sheet.
Long-form analysis from Stratechery and Daring Fireball treated the Atlassian acquisition as the more important story than the product itself. John Gruber called the price "sensible" and noted that Atlassian was effectively buying a senior product team and a credible AI browser surface for less than the cost of building one from scratch. Ben Thompson at Stratechery framed the move as Atlassian buying a way to put its own Rovo agent into the browser, where the work actually happens, rather than competing to embed AI inside individual SaaS apps.
User reception split along familiar lines. Arc loyalists were vocally upset about the pivot through much of 2025; the November 2025 update that brought back vertical tabs, sidebar mode, and Focus mode pulled some of them back. Mainstream reviewers and casual users praised the chat-with-tabs experience, in some cases describing the switching cost from Chrome as low. Critics of agentic browsing in general, including some security researchers, treated Dia as the most conservative of the AI browsers and therefore the least risky for everyday use, since Skills cannot run arbitrary code on the local machine and the assistant does not silently click through websites.