Cline

Cline is a model-agnostic autonomous coding agent that operates directly inside VS Code and the terminal¹⁾. It can create and edit files, execute commands, use a browser, and interact with any API — all with explicit user approval at every step. With over 59,000 GitHub stars, Cline is one of the most popular open-source AI coding assistants available.

GitHub: cline/cline | Website: https://cline.bot

Key Features

Plan and Act Modes — Plan Mode performs read-only analysis; Act Mode executes changes with full tool access
Model Agnostic — Works with Anthropic, OpenAI, Google Gemini, AWS Bedrock, Azure, Groq, Cerebras, and local models via Ollama or LM Studio
File Management — Creates and edits files with diff views, auto-fixes linter/compiler errors, tracks changes in VS Code Timeline
Command Execution — Runs terminal commands in real-time, monitoring output for package installs, builds, deploys, and tests
Browser Integration — Launches headless browser to click, type, scroll, capture screenshots and console logs for debugging
Checkpoints — Takes workspace snapshots at each step for easy comparison and rollback
MCP Integration — Extends capabilities through Model Context Protocol tools and a built-in MCP Marketplace²⁾
Rules System — Global and workspace-specific rules for consistent AI behavior across teams
Cost Tracking — Monitors token usage and API costs per task and per request

Architecture

Cline is built in TypeScript as a VS Code extension with a modular architecture:

Agent Loop — Iterative planning and execution cycle with human-in-the-loop approval
Tool System — File operations, terminal execution, browser automation, and MCP bridges
Context Providers — @url, @problems, @file, @folder for flexible context injection
Checkpoint Engine — Git-based workspace snapshots for state management and rollback
API Abstraction — Unified interface supporting 10+ LLM provider APIs

Usage Example

# Install via VS Code Extensions marketplace
# Search for "Cline" (formerly "Claude Dev")
 
# Or use via CLI
npx cline "add authentication middleware to the Express app"
 
# In VS Code, open the Cline sidebar and type:
# "Refactor the database module to use async/await"
# Cline will plan, show diffs, and ask for approval

How It Works

graph TD A[User Task Description] --> B{Mode Selection} B -->|Plan Mode| C[Read-Only Analysis] C --> D[Action Plan Generation] D --> E[User Review] E --> F{Approved?} F -->|Yes| G[Switch to Act Mode] F -->|No| C B -->|Act Mode| G G --> H[Tool Selection] H --> I[File Create/Edit] H --> J[Terminal Command] H --> K[Browser Action] H --> L[MCP Tool Call] I --> M[Show Diff for Approval] J --> M K --> M L --> M M --> N{User Approves?} N -->|Yes| O[Apply Change] N -->|No| P[Revise Approach] O --> Q[Checkpoint Snapshot] Q --> R{Task Complete?} R -->|No| H R -->|Yes| S[Summary Report] P --> H

Notable Characteristics

Originally released as “Claude Dev” by Saoud Rizwan, later renamed to Cline to reflect model-agnostic support.³⁾
Pioneered the human-in-the-loop approval pattern for AI coding agents in IDEs
Forked into Roo Code which added multi-mode agent architecture
Over 6,000 forks on GitHub, one of the most forked AI coding tools
Active community with regular releases and extensive marketplace of MCP extensions⁴⁾

References

¹⁾

Cline GitHub Repository

²⁾

Cline Official Documentation

³⁾

Cline Official Website. cline.bot

⁴⁾

VS Code Marketplace

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