Cline

Cline is an open-source autonomous coding agent that runs as a sidebar extension inside VS Code and other editors. Rather than suggesting code snippets you copy and paste into your files manually, Cline reads your entire codebase, creates and edits files directly, runs terminal commands, and can even drive a browser through Puppeteer for testing and automation workflows. The extension asks for your approval at each step, giving you control over what actually gets executed while still handling the mechanical work of implementation. With over five million installs, sixty-one thousand GitHub stars, and an Apache 2.0 license that allows both personal and commercial use without restriction, it has become one of the most widely adopted AI coding tools outside of commercial offerings like GitHub Copilot or Cursor. The open-source nature means you can inspect exactly what the tool does, modify it for your needs, and contribute improvements back to the community.

The workflow centers on what Cline calls Plan and Act modes, which structure how the agent approaches complex tasks. In Plan mode, you describe what you want to build or fix, and Cline outlines a strategy with specific steps before touching any code in your project. You can review each step, adjust the approach, request alternatives, or approve the plan before execution begins. This preview capability prevents the common frustration of AI tools going off in unexpected directions on multi-step tasks. In Act mode, Cline executes those steps autonomously, editing files across your project, running commands in the terminal, and responding dynamically to output from those commands. If a build fails or tests break, the agent can adjust its approach without requiring you to manually diagnose every issue. You can configure auto-approve settings for specific categories of action like read-only file operations, browser actions, or certain MCP server calls if you want faster iteration without constant approval prompts interrupting your flow.

Model Context Protocol support is where Cline pulls ahead of many alternatives in the AI coding space. MCP lets the extension connect to external servers that provide additional capabilities beyond code editing and terminal commands. Database access, API integrations, browser automation, deployment pipelines, and custom tools all become available through this protocol. Cline includes a dedicated MCP marketplace with hundreds of community-built servers that you can filter by install count, GitHub stars, category, or date added. Unlike Cursor, which caps MCP at forty tools per configuration, Cline imposes no artificial limits on how many tools you can configure simultaneously. This extensibility makes it practical for complex workflows that integrate coding with deployment, testing, database management, or external service automation. If your work involves more than just writing code, the MCP ecosystem lets you bring those adjacent tasks into the same agent-driven workflow.

The extension supports every major language model provider through your own API keys, giving you complete control over which models power your coding assistance. Anthropic Claude, OpenAI GPT, Google Gemini, AWS Bedrock, Azure OpenAI, GCP Vertex, DeepSeek, xAI Grok, Mistral, and any OpenAI-compatible endpoint all work without modification. For privacy-sensitive projects or situations where data cannot leave your local machine, local models through Ollama or LM Studio run entirely on your hardware with no external API calls whatsoever. You choose the model based on task requirements, cost constraints, and privacy considerations for each project independently. This vendor independence means you are never locked into a single provider's pricing, availability, or terms of service. If one provider raises prices or degrades quality, you switch to another without changing your tooling.

Beyond VS Code, Cline now supports JetBrains IDEs, Cursor, Windsurf, Zed, Neovim, and a preview CLI for macOS and Linux that brings the same capabilities to terminal-based workflows. The extension is completely free with no subscription tiers, usage caps, or feature gates. You pay only for the API calls to whichever model provider you choose to use, which gives you direct control over costs based on your actual usage patterns. Enterprise teams at Samsung, Salesforce, Oracle, Amazon, Microsoft, and eBay have adopted it for internal development workflows, demonstrating that the open-source model scales to large organizations with serious security and compliance requirements. For individual developers, the combination of open-source transparency, genuine multi-model support, and MCP extensibility makes Cline a practical alternative to commercial tools that lock you into specific ecosystems or charge monthly subscription fees on top of the API costs you are already paying.