Claude's built-in browser in Cowork: what AI builders should know

Anthropic has added a built-in Chromium-based browser to the Claude Cowork desktop app, letting Claude browse the web directly inside the workspace without requiring a separate extension. The feature is rolling out to paying Pro, Max, and Team plan subscribers on Mac, Windows, and Linux, and it aligns Claude with OpenAI's approach of embedding a browser in the ChatGPT desktop app rather than building a standalone browser.

Claude's Cowork desktop app now has its own Chromium browser

Until now, giving Claude the ability to use the web in Cowork meant installing the Claude in Chrome extension, which let Claude interact with pages you already had open. The new built-in browser changes that: when a task needs a website, Claude opens its own browser in a side panel, loads pages, reads them, clicks, and types. As Anthropic explains, "a lot of web tasks don't need your browser, just a browser, and now Claude has one." The Chrome extension still has a role for pages you already have open and accounts you're already signed into, but the built-in browser handles independent web tasks without the extension.

What the built-in browser changes for your workflow

For AI builders and product teams, the practical shift is reduced context switching. Instead of juggling a separate browser window or relying on the extension to pass page content to Claude, the browser lives inside the Cowork session. Claude can fill out forms, pull numbers from dashboards, or navigate internal portals without leaving the app. This mirrors a broader industry move: embedding browsing capabilities directly in AI tools to reduce reliance on external extensions or apps.

The built-in browser also supports bringing logins from Chrome, Edge, and Firefox on macOS, and Firefox on Windows and Linux. This lets Claude access authenticated sites without you manually entering credentials each time. However, Anthropic explicitly excludes logins from banking, email providers, and single sign-on sites to minimize risk. The exclusion list varies by operating system: Chrome and Edge on Windows prevent third-party apps from reading local cookies as an infostealer countermeasure, while Firefox still stores them in a plain SQLite database. On macOS, Chrome's key is in Keychain and other apps can request it from the user.

Login support, plan access, and security boundaries

The feature is limited to Pro, Max, and Team plan subscribers. If you already have the Chrome extension installed, it remains the default for web browsing unless you change the preferred browser in Claude Desktop settings. The built-in browser is "Claude's browser, not yours" -- it doesn't carry your day-to-day login info unless you explicitly import it.

Prompt injection risk remains, but the blast radius is limited

Anthropic cautions that letting an agent loose on the web always carries prompt injection risk. The company built safeguards into both the Chrome extension and the built-in browser, but notes that "the risk is not zero." Since the browser isn't likely to be logged into many sensitive sites, the blast radius is intended to be small. Builders should still evaluate their own risk tolerance, especially if Claude will interact with internal tools or authenticated services.

The bottom line for builders

The built-in browser makes Claude Cowork more self-contained for web-based agent tasks. It removes a friction point for teams that previously needed the Chrome extension, and it brings login support for common browsers while excluding the most sensitive accounts. The prompt injection caveat is real, but the design choices around login isolation and exclusion lists show Anthropic is thinking about the attack surface. If you're building workflows that require Claude to pull data from web portals or fill forms, this update simplifies the integration.