Cline: The Open-Source AI Coding Agent for VS Code & Cursor

Cline is an open-source AI coding agent that runs as an extension inside VS Code and Cursor. Unlike standard autocomplete tools, Cline can understand your entire project, edit multiple files, run terminal commands, and use a headless browser to test web apps directly from your editor.

Since Cursor is a fork of VS Code, Cline works seamlessly in both environments. It uses a "human-in-the-loop" design. Every action—whether editing a file or running a command—requires your explicit approval before execution. You review the diff before it applies.

Here is how to install, configure, and use it.

Key Features

• Autonomous Task Execution: Handles multi-step development tasks by planning, editing files, and running terminal commands.
• Plan and Act Modes: Use Plan mode to explore the codebase and map out a strategy without modifying files. Switch to Act mode to execute the plan.
• Model Agnostic: Bring your own API key. Supports Anthropic, OpenAI, Google Gemini, DeepSeek, and local models via Ollama or LM Studio.
• MCP Support: Connects to external tools, databases, and APIs via the Model Context Protocol (MCP).
• Browser Automation: Launches a browser to click, type, scroll, and capture console logs to fix runtime errors.
• Project Rules: Uses .clinerules files to enforce coding standards and architecture conventions.

Installation (VS Code & Cursor)

VS Code

1. Open VS Code (version 1.84.0 or later).
2. Open the Extensions view (Ctrl+Shift+X on Windows/Linux, Cmd+Shift+X on macOS).
3. Search for "Cline".
4. Look for the extension published by saoudrizwan with the extension ID saoudrizwan.claude-dev.
5. Click Install.
6. Once installed, click the Cline icon in the Activity Bar to open the panel.

Cursor IDE

1. Open Cursor.
2. Open the Extensions view (Ctrl+Shift+X on Windows/Linux, Cmd+Shift+X on macOS).
3. Search for "Cline" in the Open VSX Registry or VS Code Marketplace tab.
4. Click Install.
5. Click the Cline icon in the Activity Bar to open the panel.

Tip: In either IDE, drag the Cline icon to the right sidebar so your file explorer stays visible on the left.

Configuration

After installation, you need to connect Cline to an AI model. The configuration process is identical in both VS Code and Cursor. Cline offers three common paths:

1. Cline Provider (Usage-Billing): Sign in with Google/GitHub/email. No API key setup required. Pay-as-you-go.
2. ClinePass: A flat $9.99/month subscription that offers 2-5x the usage on popular open coding models compared to standard API rates.
3. Bring Your Own Key (BYOK): Use your own API key from providers like Anthropic, OpenAI, Google, OpenRouter, or local runtimes like Ollama.

Step-by-Step Configuration (BYOK)

1. Open the Cline panel in your IDE.
2. Click the Settings gear icon (⚙️) in the top-right corner.
3. Select your provider from the API Provider dropdown.
4. Paste your API Key.
5. Choose a Model from the dropdown.

// Example: Configuring Cline with an OpenAI-compatible provider
{
  "apiProvider": "openai",
  "apiKey": "sk-your-api-key-here",
  "baseUrl": "https://api.your-provider.com/v1",
  "model": "your-model-name"
}

Using Local Models (Ollama)

1. Install Ollama and pull a model:

   ollama pull qwen3
   

2. In the Cline Settings, set the API Provider to Ollama.
3. Set the Base URL to http://localhost:11434.
4. Select your model from the dropdown.

Extending with MCP Servers

MCP servers let Cline connect to external tools and data sources. You can add servers manually by editing the cline_mcp_settings.json file.

Adding an MCP Server

1. In the Cline panel, click the MCP Servers icon (server stack icon at the top of the Cline panel).
2. Select the Configure tab.
3. Click Advanced MCP Settings to open cline_mcp_settings.json.

// Example: Adding the Azure MCP Server
{
  "mcpServers": {
    "Azure MCP Server": {
      "command": "npx",
      "args": [
        "-y",
        "@azure/mcp@latest",
        "server",
        "start"
      ]
    }
  }
}

Popular MCP Servers

• Perplexity Research: Web research.
• Supabase: Hosted databases.
• Firecrawl: Web scraping.
• Prometheus Query: Metrics.

How Cline Compares to Other Tools

Since Cursor has its own built-in AI (Composer), you might wonder why you would use Cline inside it. Here is how they compare:

Cline's key differentiator is its open-source nature, granular approval workflow, and model flexibility. You can run it entirely locally if you want, and you aren't locked into Cursor's pricing structure.

Pricing

Cline itself is free and open-source (Apache 2.0). You only pay for the AI model inference costs. Here are some monthly cost estimates for an active developer:

• Cline + DeepSeek V3: $2-8/month
• Cline + Claude Sonnet: $30-80/month
• Cline + Local Model (Ollama): $0 (hardware costs only)

Note: Cline bills by token usage. It sends your file tree, open buffers, and task logs with each round, so your costs will vary depending on the model and task complexity.

Conclusion

Cline is an open-source autonomous agent for both VS Code and Cursor. It provides granular approval over every action, supports any AI model, and can be extended with MCP servers. If you want full visibility and control over your AI coding assistant—or if you want to use your own API keys inside Cursor—you can install it directly from the VS Code Marketplace or Open VSX Registry.

Links:

• Install Cline for VS Code
• Official Documentation
• GitHub Repository

References

1. Cline Official Documentation — https://docs.cline.bot
2. Cline GitHub Repository — https://github.com/cline/cline
3. Cline MCP Overview — https://mintlify.wiki/cline/cline/mcp/mcp-overview
4. Installing Cline — https://docs.cline.bot/getting-started/installing-cline
5. VS Code Marketplace — Cline Extension

#VSCode #Cursor #AI #OpenSource #DevTools