Cline
Cline
Open-source autonomous coding agent that runs as a sidebar extension inside VS Code (and JetBrains, cursor, Windsurf, Zed, Neovim). Originally released as "Claude Dev" in 2024; renamed Cline. Apache 2.0 license. 61K+ GitHub stars, 5M+ installs as of 2026. No subscription required — uses your own API keys.
How It Works
Cline runs inside the editor as a sidebar panel. You describe a task; Cline reads your project structure, plans a set of file edits and terminal commands, then executes them with your approval. Every file change is shown as a diff that can be accepted or reverted. Checkpoints allow rollback to any prior state.
Plan and Act Mode
Cline separates strategy from execution via two distinct modes:
- Plan mode: Cline reads files, runs searches, and discusses approach — but cannot modify files or run commands. Used to gather context, clarify requirements, and agree on a strategy before touching any code.
- Act mode: Full execution enabled. Cline retains the full planning context and proceeds to make file changes and run commands.
You can configure separate models for each mode — e.g., a slower reasoning model for planning and a faster/cheaper model for execution. YOLO mode allows automatic Plan→Act transition if the agent judges it ready, skipping the manual approval step.
Model Agnostic
Cline supports 30+ LLM providers: Anthropic (Claude), OpenAI, Google (Gemini), local models via ollama or lm-studio, and others. Because you provide your own API keys, costs are transparent — you see exactly what each task costs in tokens.
Key Features
- File creation, reading, editing across an entire codebase
- Terminal command execution with stdout/stderr feedback
- Browser use (navigate, click, screenshot) for testing or scraping tasks
- MCP (Model Context Protocol) support and a built-in MCP Marketplace for connecting external tools
- Linter and compiler error monitoring — fixes import errors and type mismatches as it works
- Headless execution in GitHub Actions, GitLab CI, or any pipeline
- Chat integration: trigger agents from Slack, Discord, Telegram, or Linear
Architecture (2026)
In May 2026, Cline extracted its internal agent runtime into a standalone open-source TypeScript SDK (@cline/sdk). This SDK now powers all Cline surfaces — VS Code extension, JetBrains plugin, CLI, and a Kanban task interface — rather than each surface reimplementing the agent logic.
No Subscription
Cline charges nothing. You pay the LLM provider directly at API rates. This makes costs visible and eliminates markup, but also means large agentic sessions can accumulate meaningful API charges — especially with Claude Opus or GPT-o3.
Vs. Claude Code
claude-code is Anthropic's terminal agent; it is not a VS Code extension and does not show inline diffs inside an editor. Cline is better when you want IDE integration, model flexibility, and open-source control. Claude Code is better when you want deep integration with Anthropic models, hook customization, and remote exe-dev sessions.
Related
claude-code · cursor · mcp · agentic-workflows · ollama