Cline is an open-source autonomous AI coding agent for VS Code that transforms any LLM into a powerful development assistant. With over 5 million installs and 58,000 GitHub stars, it has become one of the most popular AI coding extensions in the developer community. Cline features Plan/Act modes for structured development workflows, where Plan mode analyzes the codebase and proposes changes while Act mode executes them with user approval at each step. The extension supports Model Context Protocol (MCP) for extensibility, enabling integration with custom tools and external services. Key capabilities include automated multi-file editing, terminal command execution, browser automation for testing, and real-time debugging. Cline operates on a bring-your-own-key model with no subscription lock-in, allowing developers to use API keys from providers like Anthropic, OpenAI, or Google. The human-in-the-loop design ensures every file edit, command execution, and browser action requires explicit user approval. Trusted by engineers at Samsung, Salesforce, Microsoft, and Amazon, Cline also offers Teams and Enterprise tiers with centralized billing, role-based access control, and JetBrains IDE support.