Rating: 9.5/10 (Best Open Source Agent)

1. Executive Summary

Cline (formerly known as Claude Dev) is an open-source VS Code extension that brings autonomous agent capabilities to your local editor. Unlike proprietary tools like Windsurf or Cursor, Cline gives you full control. You bring your own API key (Anthropic, OpenAI, OpenRouter, DeepSeek), and Cline acts as a tireless junior developer.

Cline's philosophy is "Human-in-the-loop Autonomy." It can read your files, edit code, run terminal commands, and even browse the web, but it asks for permission before doing anything destructive (unless you tell it not to).

2. Core Features

2.1. The Plan -> Act Loop

Cline operates in a distinct loop:

1. Analyze: Reads your request ("Fix the bug in the login flow") and scans your file structure.
2. Plan: Proposes a set of actions ("I will read auth.ts, look for the login function, and add error handling").
3. Act: It executes the plan. It can read files, write files, run terminal commands (e.g., npm test), and analyze the output.
4. Verify: It reads the output/errors. If the test fails, it self-corrects and tries again.

2.2. Model Context Protocol (MCP) Support

Cline is a pioneer in MCP support.

• Tools: You can give Cline tools to access your Postgres database, your Linear tickets, your GitHub issues, or even browse the web (via Puppeteer).
• Extensibility: You can write your own MCP servers. For example, a company could write an MCP server that gives Cline access to their internal documentation or feature flag system.
• DeepSeek R1 Integration: In 2026, Cline became the preferred interface for the DeepSeek R1 model. Users found that combining Cline's agentic loop with DeepSeek's low cost and high reasoning capabilities created a "coding machine" that cost pennies per day.

2.3. Browser Automation

Cline can launch a headless browser to inspect your running app. It can click buttons, fill forms, and take screenshots to verify that its UI changes actually look correct.

2.4. Local Models

Cline supports Ollama and LM Studio out of the box. This means you can run Llama 3 or DeepSeek Coder locally on your GPU and have a completely offline, private coding agent.

3. Pricing

• Extension: Free (Apache 2.0 License).
• Cost: You pay the API provider (e.g., Anthropic, OpenAI) directly for token usage.
• DeepSeek: With DeepSeek's ultra-low pricing, running Cline is incredibly cheap compared to a $20/month subscription.

OpenHands

OpenHands is an open-source platform for AI software developers, acting as a generalist agent that can write code, fix bugs, and deploy applications. It automates the 'outer loop' of development, including summarizing pull requests, applying feedback, and running tests. Featuring a microagent system for domain-specific tasks, it supports real-time collaboration and includes an evaluation framework for benchmarking agent performance. OpenHands aims to reduce engineering toil by handling complex, multi-step development tasks autonomously.