Cline AI: The Most Underrated Open-Source Code Editor for Developers in 2025

In the rapidly evolving landscape of AI-powered development tools, Cline stands out as perhaps the most underrated AI code editor available today. This powerful open-source AI agent is transforming how developers write and manage code, offering unprecedented customization options and efficiency improvements that both beginners and experienced programmers can leverage.

Cline AI introduction showing its impressive 42.6k GitHub stars and highlighting its key feature of customizability across different models, editors, and prompts

What Makes Cline Different from Other AI Coding Tools

Unlike standalone applications such as Cursor and Windsurf, Cline functions as an extension within VS Code. This integration allows developers to use it in any code editor built on the VS Code platform. But what truly sets Cline apart is its completely open-source nature, providing unprecedented transparency and customization options.

Full visibility into how the AI works and its inner prompts
Ability to fork and build your own version of Cline
Opportunity to contribute improvements through pull requests
Constant evolution with regular major updates

Recent major updates have introduced game-changing features like YOLO mode, MCP marketplace, plan and act cycle, local browser automation, and numerous other enhancements. These additions have cemented Cline's position as one of the fastest-growing AI coding tools worldwide.

Getting Started with Cline: Installation and Setup

Setting up Cline is straightforward, even for those with limited technical experience. Here's how to get started:

Install VS Code from the official website
Open VS Code and navigate to the Extensions marketplace (icon on the left sidebar)
Search for "Cline" and install the extension with approximately 1.3 million downloads
Once installed, you'll see the Cline logo appear in your left sidebar

After installation, you have two options: get started for free or use your own API key to access more powerful models like Claude 3.7. For the best experience, I recommend using your own API key through OpenRouter, which provides access to various AI models.

Setting Up OpenRouter API Key for Cline

Visit OpenRouter and create an account
Add credits to your account (you may receive free credits upon signup)
Navigate to the Keys section and create a new API key
Copy the API key and paste it into Cline when prompted
Treat your API key like a password and never share it

With your API key configured, you're ready to leverage Cline's full capabilities. The platform offers impressive transparency, showing you token usage, context window utilization, and even API costs—features not readily available in alternatives like Windsurf and Cursor.

Cline's Powerful Plan and Act Cycle

One of Cline's most powerful features is its Plan and Act cycle, which significantly improves the quality of code generation. This approach breaks down development into two distinct phases:

Plan Mode: Cline creates a comprehensive project plan before writing any code
Act Mode: Once the plan is approved, Cline executes the plan step by step

This structured approach ensures that both you and the AI have a clear understanding of the project requirements and implementation strategy before any code is written. The result is more coherent, maintainable code that aligns with your vision.

Cline's planning capability demonstrated through an architecture overview diagram for a chess game application, showing the hierarchical relationship between components

YOLO Mode: Autonomous Coding with Cline

Cline's YOLO mode (also known as auto-approve) takes AI assistance to the next level by allowing the assistant to perform various actions without requesting permission for each step. This feature dramatically speeds up development and creates a more seamless experience.

When enabling YOLO mode, you can grant Cline permissions to:

Read project files
Edit project files
Execute save commands
Execute all commands (use with caution)
Use browser capabilities
Access MCP servers

You can also set the maximum number of requests Cline can make autonomously before requiring approval. A sensible range is between 10-15 requests, balancing automation with oversight.

Enhanced Checkpoints: Greater Control Over Your Workflow

Recent updates to Cline have introduced enhanced checkpoints throughout the task workflows. These checkpoints allow you to reset at different points in the development process, giving you greater control and flexibility.

For example, if you like the initial code structure but want to take a different approach for a specific feature, you can return to an earlier checkpoint while preserving your progress. This feature is particularly valuable for complex projects where requirements may evolve during development.

Project Standards Generation with /new rule

Another standout feature in recent Cline updates is the ability to generate project standards with the "/new rule" command. This feature allows Cline to autonomously create a comprehensive rule set for your entire project, establishing coding standards and practices.

This capability is particularly valuable for maintaining consistency across large codebases or when working with teams. By establishing clear standards from the outset, you can ensure that all code—whether written by humans or AI—adheres to the same quality guidelines.

Practical Example: Building a Chess Game with Cline

To demonstrate Cline's capabilities, let's examine how it approaches building a simple chess game. After entering the prompt "I want to build a simple game of chess. Create a plan for this. I want to do this in as little code as possible," Cline immediately shifts into planning mode.

The AI first outlines a comprehensive implementation strategy, including:

Core components of the chess game
Architecture overview with visual diagrams
Development phases with clear milestones
Strategies for minimizing code while maintaining functionality

After approving the plan and enabling YOLO mode, Cline begins executing the plan autonomously, creating the necessary files and implementing the chess game logic step by step.

The completed chess application built entirely by Cline AI, featuring a fully functional chessboard with pieces in starting positions and turn indicators

Token Efficiency and Cost Monitoring

One of Cline's most practical features is its transparent token usage tracking and cost monitoring. Unlike many competitors, Cline clearly displays:

Tokens used in each prompt and response
Percentage of the context window utilized
Estimated API cost for each interaction

This transparency is invaluable for developers and teams working with budget constraints, allowing for more efficient use of AI resources. Recent updates have further improved Gemini caching, saving even more tokens when using Google's models.

JAVASCRIPT

// Example of minimalist chess piece movement logic generated by Cline
function movePiece(fromSquare, toSquare) {
  const piece = board[fromSquare.row][fromSquare.col];
  
  if (isValidMove(piece, fromSquare, toSquare)) {
    // Execute the move
    board[toSquare.row][toSquare.col] = piece;
    board[fromSquare.row][fromSquare.col] = null;
    
    // Switch turns
    currentPlayer = currentPlayer === 'white' ? 'black' : 'white';
    updateGameStatus();
    return true;
  }
  
  return false;
}

Cline for Non-Technical Users

A significant advantage of Cline is its accessibility for non-technical users. While it offers advanced features for experienced developers, beginners can also leverage its capabilities to learn coding and build projects without extensive programming knowledge.

If you encounter any issues during setup or use, modern AI tools like ChatGPT can help troubleshoot problems. Simply send a screenshot and describe what's happening, and you'll likely receive a solution quickly. This support system makes Cline approachable for users at all skill levels.

The Benefits of Open Source

Cline's open-source nature provides several advantages over proprietary alternatives:

Transparency: You can see exactly how the AI operates and what prompts it uses
Customization: Modify Cline to suit your specific development needs
Community improvements: Benefit from enhancements made by other developers
Future-proofing: Even if official development ceased, the community could maintain the tool
Integration flexibility: Adapt Cline to work with your existing development stack

These benefits make Cline not just a tool but a platform that can evolve with your needs and the broader development landscape.

Conclusion: Why Cline Deserves More Recognition

Cline represents a significant advancement in AI-assisted coding tools, offering a powerful, transparent, and customizable alternative to better-known options. Its open-source nature, combined with features like the Plan and Act cycle, YOLO mode, and enhanced checkpoints, make it an invaluable tool for developers of all skill levels.

As AI continues to transform software development, tools like Cline that prioritize developer agency, transparency, and customization will become increasingly important. Whether you're a professional developer looking to streamline your workflow or a beginner taking your first steps into coding, Cline offers capabilities that can significantly enhance your productivity and learning experience.

Give Cline a try and discover why it's quickly becoming a favorite among developers who value both power and flexibility in their AI coding assistants.

Cline AI: Why This Underrated Open-Source Code Editor Is Revolutionizing Development