Cline is an open-source coding agent that works inside the editor or in the terminal. Rather than only suggesting lines, it reads the repository, proposes a plan, edits files, runs commands and shows every step for approval before applying it.
What it’s for
- Implementing multi-step coding tasks from a natural-language description
- Creating, editing and reviewing files directly in the project workspace
- Running terminal commands and using the result to correct its own path
- Connecting external tools and context sources through MCP
- Running multi-agent flows or a headless/CLI mode for automation
How it works
- You choose the provider and model and supply your own key (BYO-model)
- The agent follows a plan, act and observe loop, showing diffs and asking for confirmation on actions with side effects, such as writing files or running commands
- Project context is read on demand; rules and instructions can be pinned in repository files
- The same base serves the IDE extension, CLI and SDK, so the flow can be reused in automation
Where it runs
- VS Code and derivatives, as an extension
- JetBrains IDEs, through a dedicated extension
- Terminal/CLI and headless execution
- Editor side panel, with diff-based review
Availability and licensing
- Core is open source under Apache-2.0; the JetBrains extension is distributed separately
- Model-agnostic: quality and consumption depend on the chosen model provider
- No Cline subscription is required to use models on your own account
Strengths
- Independence from model vendor and editor
- Explicit human approval before actions with repository side effects
- MCP ecosystem for tools and context
- Auditable open source
Things to note
- The agent runs real commands; reviewing permissions and diffs is part of the flow
- Consumption and cost vary with the model and context size
- Capabilities may differ across extension, CLI and SDK