The AI web browser Dia is drawing inspiration from its predecessor, Arc, an earlier experiment in modernizing the web browsing experience that hailed from the startup known as The Browser Company. On Sunday, The Browser Company founder Josh Miller confirmed that the new AI browser will bring “Arc’s greatest hits” to Dia, including things like the sidebar mode, and combine that with AI-native features like memory and agents.
This explanation suggests that Dia, which has since been acquired by Atlassian for $610 million, could have an advantage in the AI browser race, as it builds on the company’s earlier learnings from developing Arc.
The latter was initially released in mid-2023 as a reinvention of the browser designed around the way people use the internet today. That included offering separate workspaces for work and personal browsing, support for pinned tabs, a Command Bar that worked like Apple’s Spotlight search, and a sidebar that included the search bar, tab list, user bookmarks, audio controls, and more.
Tbh we (or i really) duffed the comms in a bunch of ways, but…1. Dia’s architecture is much better for AI, speed, security2. We’re adapting Arc’s greatest hits to be native to Dia3. Sidebar mode for Arc fansDia + Arc = snappier, smarter, simpler by default w/ Pro mode— Josh Miller (@joshm) November 3, 2025
However, Arc may have tried to push the envelope a bit too far: Miller later admitted that Arc was ultimately too complex for most people to adopt.
“Arc was simply too different, with too many new things to learn, for too little reward… On top of that, Arc lacked cohesion in both its core features and core values. It was experimental, that was part of its charm, but also its complexity,” Miller wrote in a blog post earlier this year, detailing the company’s decision to wind down Arc and open source it, and refocusing the company’s efforts on building Dia.
But Arc may not necessarily be a failure, even if it didn’t become a widely adopted consumer product. Instead, the browser gave the company a year-plus’ worth of insights into what sort of modern browser features resonate with users and which ones do not.
That could help the company get ahead when building out the feature set for Dia.
As Miller says in a post on X, “Dia’s architecture is much better for AI, speed, and security,” but it will introduce features that Arc fans loved, like the sidebar mode — which …