Adopting AI in a professional setting raises a fundamental question: is my data safe? With Claude Cowork, Anthropic offers an AI agent that works directly on your machine in a sandboxed environment. But what actually happens with your files? What GDPR guarantees do you have? This article answers all these questions with concrete recommendations for using Claude Cowork securely, even when handling sensitive data.
How Claude Cowork handles your data
Claude Cowork operates on a specific architectural model. When you launch a task, the agent runs in a virtualized sandbox environment on your own machine. Your files — spreadsheets, Word documents, PDFs, databases — are read and manipulated locally.
However, text exchanges between you and Claude pass through Anthropic's servers. Every prompt you send and every response generated goes through the Claude API. This raises the central question: what data leaves your machine, and how is it handled on Anthropic's servers?
What is sent to Anthropic servers
- Your text instructions: every message you type in the Cowork interface.
- Referenced file content: if you ask Claude to analyze a file, relevant content is sent in the conversation context.
- Execution results: when Claude runs code or commands, outputs are sent back to the model so it can continue the task.
What stays on your machine
- Your original files: they are not permanently copied to Anthropic's servers.
- The sandbox environment: all executed code, temporary files, and modifications remain in the local container.
- Your project history: CLAUDE.md files, custom instructions, and project notes stay on your disk.
GDPR compliance: where does Anthropic stand?
Anthropic has published a Data Processing Agreement (DPA) compliant with the European Commission's standard contractual clauses. Key commitments include:
- Purpose limitation: data transmitted via the API is processed solely to deliver the requested service.
- No training on your data: since March 2024, Anthropic commits to not using API and Cowork user data for model training without explicit consent.
- Limited retention: conversation data is kept for 30 days for safety and abuse monitoring, then deleted.
- Identified sub-processors: Anthropic publishes its sub-processor list (primarily AWS) with change notifications.
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