What it is
Cline is an open-source autonomous coding agent that lives inside VS Code, originally built by Saoud Rizwan in 2024. It started as the project "claude-dev" and grew into one of the most popular community VS Code agents — over 1 million installs on the Marketplace as of 2026. The core proposition: bring-your-own-API-key, control every tool call with auto-approve patterns, and keep everything open source under Apache-2.0.
It is the tool to reach for when:
- You want an autonomous VS Code agent without paying a Copilot subscription.
- You want to bring your own model — Claude, OpenAI, Gemini, OpenRouter, local Ollama, even DeepSeek.
- You want fine-grained control over which actions auto-execute and which require human approval.
Why it stands out
| Feature | What it gives you |
|---|---|
| Bring-your-own-key | Plug in any model — Anthropic, OpenAI, Gemini, OpenRouter, Ollama, vLLM |
.clinerules |
Project-level instruction file (vendor-neutral; Roo Code reads it too) |
| Auto-approve patterns | Whitelist regex for which shell commands / file writes auto-execute |
| Browser tool | Built-in headless browser for testing and scraping inside the agent loop |
| MCP support | Full MCP client; reuse Claude Code MCP servers |
| Token cost panel | Per-message cost breakdown — see exactly what each turn cost |
| Apache-2.0 | Source on GitHub, fork-friendly (Roo Code is the most popular fork) |
How to install
# In VS Code
code --install-extension saoudrizwan.claude-dev
# Or open Extensions panel and search "Cline"
After install, open the Cline panel from the sidebar and paste an Anthropic / OpenAI / OpenRouter API key. Drop a .clinerules in your project root with conventions and Cline reads it on every task.
What to install in Cline
Cline reads two project-level files: .clinerules (instructions) and ~/Documents/Cline/MCP/ for MCP servers. Three TokRepo packs to start:
- .clinerules Templates — vendor-neutral instruction files for popular stacks (also used by Roo Code)
- Cline Auto-Approve Patterns — battle-tested allowlists for read-only commands, package managers, formatters
- MCP Server Stack — Postgres / GitHub / Filesystem servers shared across Cline / Claude Code / Codex
tokrepo install lays down all three and you have the same baseline most senior Cline users start from.
Common pitfalls
- Auto-approve scope creep — start strict (only
npm test,git status). Loosen one pattern at a time. Auto-approvingrm -rf— even by accident in a regex — is unrecoverable. - API key in chat history — Cline stores tasks locally; if you paste an API key into a message it lives in the task file. Use env vars or settings.
- Browser tool resource leak — the headless browser keeps tabs alive across tasks. Use the "close all browser tabs" button or it'll eat RAM.
- MCP server path differences — Cline uses
~/Documents/Cline/MCP/not.claude/. Symlinking works but is brittle; usetokrepo migrateinstead. - Long-running tasks lose context on VS Code reload — Cline saves task state but a VS Code crash can corrupt it. For long refactors, prefer the terminal CLIs.
Relationship to other tools
Cline pioneered the "VS Code agent with BYOK + auto-approve" niche that GitHub Copilot's agent mode and Cursor's composer later filled with first-party offerings. The community fork Roo Code added modes (architect/code/ask/debug) and Boomerang task delegation. Compared to Claude Code, Cline lives in the IDE rather than the terminal — better for visual review, weaker for headless CI. Most senior users in 2026 either use Cline as their main IDE agent (BYOK savings vs Copilot) or run Cline alongside Claude Code (one in IDE, one in terminal).
Most-installed for Cline
6 assets that work with Cline
Frequently asked questions
Is Cline free?
Cline itself is Apache-2.0 open source and free. You only pay for the model API tokens it consumes — and you control which model. Many users pair Cline with Anthropic API directly, Claude.ai max, or OpenRouter for cheap rotating models. There's no Cline subscription.
What's the difference between Cline and Roo Code?
Roo Code is a community fork of Cline that adds explicit modes (architect, code, ask, debug) and Boomerang task delegation between modes. Cline stays closer to the original single-agent design. Both share .clinerules so configs port between them. Choice is mostly preference.
Does Cline work with Claude Code subagents?
Not directly — subagents are a Claude Code-specific format. But Cline supports MCP servers, so any MCP server you set up for Claude Code works in Cline. The vendor-neutral .clinerules is also recognized by Roo Code, so project-level instructions port.
Cline vs GitHub Copilot agent mode — which should I pick?
Pick Cline if you want BYOK (use any model with your own key), open-source code, fine-grained auto-approve, or you don't want to pay a Copilot subscription. Pick Copilot if you want managed billing, enterprise SSO/audit, and the deepest VS Code integration. Cline gives more control; Copilot gives more polish.
Can Cline run headless or in CI?
Not really — it's a VS Code extension and requires the IDE to host it. For CI, pair Cline (in your IDE during development) with Claude Code or Codex CLI (in CI). The .clinerules file ports to both vendor-neutral terminal agents.
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