Anthropic released its Claude Cowork AI agent software for Windows on Monday, bringing the file management and task automation tool to roughly 70 percent of the desktop computing market and intensifying a remarkable corporate realignment that has seen Microsoft embrace a direct competitor to its longtime AI partner, OpenAI.

The Windows launch arrives with what Anthropic calls "full feature parity" with the macOS version: file access, multi-step task execution, plugins, and Model Context Protocol (MCP) connectors for integrating external services. Users can now also set global and folder-specific instructions that Claude follows in every session, a feature developers on Reddit described as "a game-changer" for maintaining context across projects.

"Cowork is now available on Windows," Anthropic announced on X. "We're bringing full feature parity with MacOS: file access, multi-step task execution, plugins, and MCP connectors."

The release closes a critical platform gap that had limited Cowork to Apple's operating system since its January 12 debut. The Windows expansion underscores a broader transformation already underway in enterprise AI, with Microsoft simultaneously selling its own GitHub Copilot to customers while encouraging thousands of its own employees to adopt Anthropic's competing tools internally.

Inside Microsoft's surprising pivot toward its biggest AI rival

The relationship between Microsoft and Anthropic has accelerated with striking speed. In November, the two companies announced a strategic partnership allowing Microsoft Foundry customers access to Claude Sonnet 4.5, Claude Opus 4.1, and Claude Haiku 4.5. As part of that arrangement, Anthropic committed to purchasing $30 billion of Azure compute capacity.

But the partnership has expanded well beyond cloud hosting. According to a January...