Cline

What is Cline about?

Cline brings agentic AI capabilities into the development workflow. Leveraging Claude 3.7 Sonnet, it can understand project structure, read source code, and perform complex coding tasks autonomously while keeping a human‑in‑the‑loop safety model.

How to use Cline?

1. Install the extension from the VS Marketplace.
2. Open the command palette (CMD/CTRL + Shift + P) and select Cline: Open In New Tab.
3. Enter a natural‑language task (e.g., "convert this mockup into a functional React component" or "fix the failing tests").
4. Approve each file change or terminal command when prompted. Cline will display diffs, command outputs, and browser screenshots for review.
5. After completion, execute the suggested final command (e.g., opening the generated page) with a single click.

Key features of Cline

• File creation & editing: Generates, modifies, and previews diffs inside the editor; monitors linters and compilers to auto‑fix errors.
• Terminal integration: Runs shell commands via VS Code’s shell‑integration API, captures output, and reacts to runtime issues.
• Browser automation: Launches a headless browser, performs clicks, typing, scrolling, and captures screenshots/console logs for visual debugging.
• Model Context Protocol support: Can create and install custom MCP tools on‑the‑fly to extend its capabilities (e.g., Jira fetcher, AWS EC2 manager).
• Context injection: @url, @problems, @file, @folder shortcuts let users add external docs, workspace errors, or files instantly.
• Checkpoints & rollback: Snapshots workspace after each step; compare and restore to any previous state.
• Multi‑model API support: Works with OpenRouter, Anthropic, OpenAI, Google Gemini, AWS Bedrock, Azure, GCP Vertex, Cerebras, Groq, or any OpenAI‑compatible endpoint.
• Cost tracking: Shows token usage and estimated API cost per request and for the whole task.

Use cases of Cline

• Transforming design mockups (images) into production‑ready front‑end code.
• Debugging and fixing failing builds or test suites automatically.
• Performing end‑to‑end web UI testing by controlling the browser.
• Automating repetitive dev tasks such as dependency upgrades, lint fixes, or scaffolding new modules.
• Extending workflows with custom tools (e.g., fetching tickets from Jira, managing cloud resources).

FAQ from Cline

Q: Do I need to write prompts in a specific format? A: No. Describe the task in natural language; Cline will ask for clarification if needed.

Q: Is the extension safe to run commands on my machine? A: All terminal commands and file modifications require explicit user approval before execution.

Q: Which models can I use? A: Any supported provider listed in the settings, including Anthropic Claude, OpenAI GPT, Google Gemini, and community‑hosted OpenAI‑compatible endpoints.

Q: Can Cline work with large codebases? A: Yes. It indexes the project, reads ASTs, and selectively adds files to context to stay within model limits.

Q: How do I add a custom tool? A: Ask Cline to "add a tool that …"; it will generate the MCP server, install it, and make it available for future tasks.

Cline – #1 on OpenRouter

Meet Cline (pronounced /klaɪn/, like "Klein"), an AI assistant that can use your CLI aNd Editor.

Thanks to Claude 3.7 Sonnet's agentic coding capabilities, Cline can handle complex software development tasks step-by-step. With tools that let him create & edit files, explore large projects, use the browser, and execute terminal commands (after you grant permission), he can assist you in ways that go beyond code completion or tech support. Cline can even use the Model Context Protocol (MCP) to create new tools and extend his own capabilities. While autonomous AI scripts traditionally run in sandboxed environments, this extension provides a human-in-the-loop GUI to approve every file change and terminal command, providing a safe and accessible way to explore the potential of agentic AI.

1. Enter your task and add images to convert mockups into functional apps or fix bugs with screenshots.
2. Cline starts by analyzing your file structure & source code ASTs, running regex searches, and reading relevant files to get up to speed in existing projects. By carefully managing what information is added to context, Cline can provide valuable assistance even for large, complex projects without overwhelming the context window.
3. Once Cline has the information he needs, he can:
   • Create and edit files + monitor linter/compiler errors along the way, letting him proactively fix issues like missing imports and syntax errors on his own.
   • Execute commands directly in your terminal and monitor their output as he works, letting him e.g., react to dev server issues after editing a file.
   • For web development tasks, Cline can launch the site in a headless browser, click, type, scroll, and capture screenshots + console logs, allowing him to fix runtime errors and visual bugs.
4. When a task is completed, Cline will present the result to you with a terminal command like open -a "Google Chrome" index.html, which you run with a click of a button.

[!TIP] Use the CMD/CTRL + Shift + P shortcut to open the command palette and type "Cline: Open In New Tab" to open the extension as a tab in your editor. This lets you use Cline side-by-side with your file explorer, and see how he changes your workspace more clearly.

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Use any API and Model

Cline supports API providers like OpenRouter, Anthropic, OpenAI, Google Gemini, AWS Bedrock, Azure, GCP Vertex, Cerebras and Groq. You can also configure any OpenAI compatible API, or use a local model through LM Studio/Ollama. If you're using OpenRouter, the extension fetches their latest model list, allowing you to use the newest models as soon as they're available.

The extension also keeps track of total tokens and API usage cost for the entire task loop and individual requests, keeping you informed of spend every step of the way.

Run Commands in Terminal

Thanks to the new shell integration updates in VSCode v1.93, Cline can execute commands directly in your terminal and receive the output. This allows him to perform a wide range of tasks, from installing packages and running build scripts to deploying applications, managing databases, and executing tests, all while adapting to your dev environment & toolchain to get the job done right.

For long running processes like dev servers, use the "Proceed While Running" button to let Cline continue in the task while the command runs in the background. As Cline works he’ll be notified of any new terminal output along the way, letting him react to issues that may come up, such as compile-time errors when editing files.

Create and Edit Files

Cline can create and edit files directly in your editor, presenting you a diff view of the changes. You can edit or revert Cline's changes directly in the diff view editor, or provide feedback in chat until you're satisfied with the result. Cline also monitors linter/compiler errors (missing imports, syntax errors, etc.) so he can fix issues that come up along the way on his own.

All changes made by Cline are recorded in your file's Timeline, providing an easy way to track and revert modifications if needed.

Use the Browser

With Claude 3.5 Sonnet's new Computer Use capability, Cline can launch a browser, click elements, type text, and scroll, capturing screenshots and console logs at each step. This allows for interactive debugging, end-to-end testing, and even general web use! This gives him autonomy to fixing visual bugs and runtime issues without you needing to handhold and copy-pasting error logs yourself.

Try asking Cline to "test the app", and watch as he runs a command like npm run dev, launches your locally running dev server in a browser, and performs a series of tests to confirm that everything works. See a demo here.

"add a tool that..."

Thanks to the Model Context Protocol, Cline can extend his capabilities through custom tools. While you can use community-made servers, Cline can instead create and install tools tailored to your specific workflow. Just ask Cline to "add a tool" and he 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.

• "add a tool that fetches Jira tickets": Retrieve ticket ACs and put Cline to work
• "add a tool that manages AWS EC2s": Check server metrics and scale instances up or down
• "add a tool that pulls the latest PagerDuty incidents": Fetch details and ask Cline to fix bugs

Add Context

@url: Paste in a URL for the extension to fetch and convert to markdown, useful when you want to give Cline the latest docs

@problems: Add workspace errors and warnings ('Problems' panel) for Cline to fix

@file: Adds a file's contents so you don't have to waste API requests approving read file (+ type to search files)

@folder: Adds folder's files all at once to speed up your workflow even more

Checkpoints: Compare and Restore

As Cline works through a task, the extension takes a snapshot of your workspace at each step. You can use the 'Compare' button to see a diff between the snapshot and your current workspace, and the 'Restore' button to roll back to that point.

For example, when working with a local web server, you can use 'Restore Workspace Only' to quickly test different versions of your app, then use 'Restore Task and Workspace' when you find the version you want to continue building from. This lets you safely explore different approaches without losing progress.

Contributing

To contribute to the project, start with our Contributing Guide to learn the basics. You can also join our Discord to chat with other contributors in the #contributors channel. If you're looking for full-time work, check out our open positions on our careers page!

License

Apache 2.0 © 2025 Cline Bot Inc.