Cline

Cline is one of the most influential open-source coding agents of the last two years. It installs as a VS Code or JetBrains extension and connects directly to your provider of choice (Anthropic, OpenAI, Google, OpenRouter, Bedrock, Vertex, Groq, Fireworks, Together, or local Ollama and LM Studio models). Unlike proprietary agents, Cline shows every proposed file edit, terminal command, and tool call before it runs, with an approve/reject step that keeps the developer in the loop. The agent maintains a plan, a work log, and a checkpoint history so you can rewind changes if a run goes wrong. Plan Mode lets Cline think through complex tasks without touching files, while Act Mode executes changes. Cline's MCP support is a defining feature: it can discover, install, and use MCP servers on demand — even asking the model to build a new server for a task if none exists — giving it access to browsers, databases, cloud APIs, and enterprise systems. The project is BYO-key by design, so cost is fully transparent and pass-through to the underlying model provider; there is no Cline platform fee. That combination of open source, provider agnosticism, and explicit tool-use makes Cline the tool many teams reach for when they want an agent they can audit line-by-line.