Cline

What Is Cline?

Cline is an open-source AI coding agent that runs inside VS Code (and JetBrains IDEs) and turns any capable LLM into a hands-on development collaborator. It can handle complex software development tasks step-by-step, with tools that let it create and edit files, explore large projects, use a browser, and execute terminal commands after you grant permission. That last part matters: it provides a human-in-the-loop GUI to approve every file change and terminal command, giving you a safe and accessible way to explore agentic AI.

The name is literally an acronym: CLI aNd Editor. That origin story tells you a lot about who built it and for whom.

Who It Is For

Cline is aimed squarely at developers who want an agent that works across an entire codebase rather than just autocompleting lines. It is best for codebases where you want step-by-step, tool-using assistance: refactors, feature work, debugging, scaffolding, and repo-wide edits. If your primary need is fast inline suggestions while you type, this is not your tool. Cline focuses on agentic coding (multi-file edits, autonomous tasks) rather than inline autocomplete. For inline suggestions, GitHub Copilot is the fastest.

It has crossed 5 million installs, which is a real signal that it is not just a niche power-user toy. The project is fully open source on GitHub, so you can inspect what it does, contribute, or self-host.

How It Actually Works

You give Cline a task in natural language. In Plan mode, it breaks the task down and shows you what it intends to do before touching anything. In Act mode, it executes. At every step where it would write a file or run a terminal command, it pauses and asks for your approval. It has a human-in-the-loop design with approval required for every file change and command execution.

Thanks to the Model Context Protocol (MCP), Cline can create new tools and extend its own capabilities. In practice this means you can ask Cline to, say, "add a tool that fetches Jira tickets" and it will handle everything, from creating a new MCP server to installing it into the extension. These custom tools then become part of Cline's toolkit, ready to use in future tasks.

Cline also supports JetBrains IDEs with all core features including diff editing, tools, multiple API providers, MCP servers, and Cline rules/workflows. There is also a CLI in preview for macOS and Linux, useful for CI/CD pipelines and multi-instance workflows.

Pricing

Cline's pricing model is different from Cursor or Copilot. For light users, the pay-per-token approach can be cheaper than subscriptions. For heavy users, it can be more expensive. Setup requires API keys; you need to bring your own.

Cline is open source and supports providers like Anthropic, Gemini, OpenAI, OpenRouter, AWS Bedrock, GCP Vertex, Groq, Cerebras, and DeepSeek. You're never locked into their platform or pricing. Model flexibility is a genuine selling point here.

Strengths and Limitations

Strengths include high-quality plans, sensible tool usage, low token spend optimizations, and strong results with top models. The open-source nature means the community moves fast and the codebase is auditable.

The limitations are real though. It requires API costs and can sometimes be over-aggressive with changes.

Quality is model-dependent, and long sessions can still be pricey. If you put a weak model behind it, you get weak results. Token costs on a heavy refactor session with Claude Sonnet can surprise you. This is the honest tradeoff for the depth of context it maintains.

Power users who want maximum control should try Cline, but if you want something that works well out of the box with minimal configuration, you might find the BYOK setup friction annoying at first. Once you are past that, it is one of the more capable and transparent agents available today.