DeepClaude is a project that allows users to use Claude Code's autonomous agent loop with DeepSeek V4 Pro, OpenRouter, or other Anthropic-compatible backends, reducing costs by up to 17 times. The project works by swapping the brain of Claude Code with a cheaper alternative, while keeping the same user experience. This is achieved by setting environment variables that determine which API endpoint to use, allowing users to switch between different backends. The project also provides a proxy that tracks token usage and calculates cost savings.