Cline AI Review 2026: Open-Source VS Code Coding Agent Tested
Cline is an open-source autonomous coding agent for VS Code with 5M+ installs and 58,000+ GitHub stars. Unlike Cursor or Copilot, it runs inside your existing VS Code installation, uses your own API keys, and executes multi-step tasks autonomously — reading files, running terminal commands, and testing in a headless browser. It’s not a code autocomplete tool. It’s a full agent that works until the task is done. What Is Cline and How Does It Work? Cline is an open-source VS Code extension that functions as an autonomous AI coding agent — not a tab-completion assistant. Installed as a standard extension (not a VS Code fork), Cline brings in a separate agent panel where you describe tasks in natural language. It plans multi-step solutions, reads and writes files across your codebase, executes terminal commands to install packages or run builds, and even controls a headless browser to verify UI changes. In 2026, Cline has 5M+ VS Code extension installs and 58,000+ GitHub stars, making it the most-adopted open-source coding agent in the ecosystem. The core architectural decision that separates Cline from competitors: every action — file edit, terminal command, or browser interaction — triggers an approval gate before execution. This human-in-the-loop design means Cline rarely takes destructive actions without your explicit sign-off. You bring your own API key (BYOK), connect it to Anthropic, OpenAI, Google, Mistral, DeepSeek, or a local Ollama model, and pay only for model usage. There is no subscription to Cline itself. ...