Cline Guide 2025: Open-Source AI Coding Assistant for VS Code

What Is Cline?

Cline (formerly Claude Dev) is an open-source AI coding agent for VS Code. The key difference from tools like Cursor or GitHub Copilot is that Cline is bring-your-own-API-key (BYOK) — you pay AI providers directly, with zero Cline subscription fee.

Cline runs as a VS Code extension, so it works inside your existing editor without switching tools. Its agent capabilities include:

• File editing — reads, creates, and edits files across your project
• Terminal commands — executes shell commands (npm install, pytest, git, etc.)
• Browser automation — can control a headless browser to test web apps
• MCP servers — connects to external tools via Model Context Protocol
• Diff review — shows a VS Code diff for every file change before applying

Cline is MIT-licensed and has over 30,000 GitHub stars, making it the most popular open-source AI coding agent.

Installation

Install Cline directly from the VS Code Marketplace:

1. Open VS Code and press Ctrl+Shift+X (Cmd+Shift+X on Mac)
2. Search for "Cline" — look for the extension by saoudrizwan
3. Click Install
4. A Cline icon appears in the Activity Bar (left sidebar) — click it
5. In the Cline panel, go to Settings and enter your API key

Supported Models

Cline supports virtually every major AI provider. Configure your preferred one in the Cline settings panel:

You can switch models between tasks. Many developers use DeepSeek for rapid iteration and Claude for final, complex refactors.

API Cost Control

Because Cline uses your own API keys, keeping an eye on costs is important. Cline provides several built-in cost controls:

• Token budget per task: Set a maximum token spend per task — Cline pauses and asks before exceeding it
• Cost display: Cline shows the running token count and estimated cost in the panel during every task
• Model switching: Use a cheap model (DeepSeek) for exploration, switch to Claude for final edits
• Approval mode: Set Cline to ask for approval before every file edit or terminal command

MCP Server Support

Cline has first-class support for MCP (Model Context Protocol) servers. Connect Cline to GitHub, databases, Slack, file systems, browser tools, and hundreds of other integrations. MCP servers are configured in the Cline settings panel — no manual JSON editing required.

Popular MCP servers for Cline include: GitHub (create PRs, read issues), PostgreSQL (query databases), Playwright (browser automation), and Filesystem (enhanced file operations). Browse available servers at prismix.dev/mcp.

Cline vs Cursor vs Claude Code

See also: Cursor Guide, Cursor vs Cline, and Windsurf Guide. Note: Cline installs inside Windsurf too, so you can combine Windsurf's Supercomplete with Cline's MCP tooling.

Tips for Getting the Most Out of Cline

• Start with approval mode on: Until you trust Cline's behavior with your codebase, require approval before every file change and terminal command. You can turn off approvals for specific tools once you're comfortable.
• Use .clinerules: Create a .clinerules file in your project root to set persistent instructions (like a CLAUDE.md for Cline).
• Pair with DeepSeek for cost control: Use DeepSeek V3 for file reading and exploration tasks; switch to Claude or GPT-4o only for the final implementation step.
• Local models for privacy: Configure Cline with Ollama to run entirely locally — no data leaves your machine. Suitable for air-gapped or IP-sensitive environments.