Cline

Cline (formerly Claude Dev) is an open-source VS Code extension that gives you an autonomous AI agent directly inside your editor — it can read files, run terminal commands, browse the web, and iterate until a task is done. As of early 2026 it has 58K+ GitHub stars and 5M+ developers.

Why It's in Trial

Cline is one of the most capable open-source agentic tools for VS Code. Its Plan/Act workflow and model flexibility make it a strong choice for teams wanting control over their AI agent:

• Plan/Act modes: Cline's standout feature. Plan mode lets the AI analyze your codebase and lay out a step-by-step approach without touching any files. Act mode then executes with your approval at each step — keeping humans in the loop without losing automation.
• Full agent loop: Cline plans tasks, executes steps, reads output, and adjusts — all within VS Code.
• MCP integration: Deep Model Context Protocol support, including the ability to create and install custom MCP servers on demand, extending what the agent can do.
• Browser access: Optional computer use lets Cline open browsers, take screenshots, and interact with UIs.
• Model freedom: Anthropic, OpenAI, Google Gemini, AWS Bedrock, Azure, GCP Vertex AI, Groq, Cerebras, LM Studio, Ollama, and OpenRouter — giving you full cost and compliance control.
• Transparent actions: Every file read, write, and command is shown to you before execution (or use YOLO mode to auto-approve all actions).

Getting Started

1. Install "Cline" from the VS Code extension marketplace
2. Open the Cline panel and enter your API key (Anthropic, OpenAI, etc.)
3. Describe a task — e.g. "Build a REST API endpoint that returns the current weather for a city"
4. Use Plan mode first to review the approach before Cline starts making changes

Security Considerations

Cline's YOLO mode auto-approves all file writes and shell commands without prompting — convenient for speed, but it removes the human-in-the-loop safety check entirely. Use Plan mode first on unfamiliar tasks, and reserve YOLO mode for well-understood, low-risk workflows.

As an IDE-embedded agent with MCP support and browser access, Cline is also exposed to MCP security risks (see MCP Security Best Practices): tool poisoning, prompt injection via fetched data, and token theft via misconfigured MCP servers. Treat MCP servers you didn't write with the same scrutiny as third-party dependencies. See AI Agent Sandboxing on the Security radar for OS-level isolation options that can be layered on top.

Cost Awareness

Because Cline sends large amounts of context (files, terminal output) to the model on every step, costs can add up quickly. Monitor your API usage and set spending limits on your API account. Cline also offers a team tier at $20/month (first 10 seats free) with additional management features.

Key Characteristics