The Browser Company announced Thursday that Arc will stop working on Mac and Windows on December 22. Anyone who has followed the company since 2025, when feature work on Arc stopped and the team moved to its AI browser Dia, saw this coming. The stated reason deserves a closer look, though, because it doesn’t quite hold together.
The security argument has a hole in it
The official line is about security. “Keeping a browser secure takes constant, dedicated work that is only increasing in the age of AI,” the company wrote, adding that Dia “was built from the ground up to meet today’s security standards.”
Fair enough on the first part. Maintaining a browser is relentless patch work, and a small team can’t carry two of them forever. But CEO Josh Miller previously explained why Arc couldn’t simply be open-sourced. It runs on the Arc Development Kit, a proprietary SDK that is also the core engine powering Dia. “We can’t do that meaningfully without also open-sourcing ADK,” he said, “and ADK is still core to our company’s value.”
Put those two statements side by side. If Dia runs on Arc’s engine, “built from the ground up” is marketing. If it doesn’t, the ADK excuse for keeping Arc closed is weaker than it sounds. I think the first reading is closer to the truth. Dia is Arc’s engine with a chatbot on top, and Arc is being switched off because the company wants its users where the AI features are. Atlassian, which bought The Browser Company for $610 million in 2025, presumably wants the same thing.
That’s a legitimate business decision. I’d respect it more if it were described as one.
The schedule is tight
The wind-down comes in stages. New Arc accounts were blocked as of Thursday. On November 23, Arc Search on iOS and Android loses its AI features, including Browse for Me, along with sign-in and tab sync. It keeps working as a basic local browser. On December 22 the desktop app stops working, accounts are deactivated, and personal data is deleted within 30 days. Arc Search also gets pulled from the Google Play Store.
Two months is short notice for a browser people organized their working lives around. Arc users built habits on Spaces, folders and the vertical sidebar. Killing the desktop app outright, instead of letting it run unsupported behind a loud warning, is the harshest option on the table.
What Dia offers Arc people
To its credit, the migration looks decent. Passwords, bookmarks, extensions and history transfer over. Spaces become Profiles, Folders become Pinned Tab Groups, and vertical tabs survive as an optional sidebar layout. The Arc-style features stay free and the AI is optional. The company also says Dia beats Arc on speed, stability and security benchmarks. Those are the company’s own numbers.
The AI side is, as Engadget put it, more or less a standard AI browser: a chatbot that reads context across open tabs, summaries of emails and YouTube videos, and a daily “morning brief” built from calendars, inboxes and links. Some people will find that useful. It isn’t why anyone fell for Arc.
Arc’s problem was always what the company itself called the “novelty tax.” Enthusiasts loved it and mainstream users bounced. Dia is the attempt to keep the interface ideas while selling what every other AI browser is selling. Arc loyalists get a reasonable new home, with a chat panel they can ignore.
What remains unanswered is the open-source promise. Miller said he’d “love to open-source Arc someday.” With the app dead in December and account data gone by late January, does someday ever arrive?