Is Claude Code open source? No, it is proprietary software

Claude Code is not open source. The LICENSE.md file in Anthropic's claude-code repository on GitHub says only: "© Anthropic PBC. All rights reserved. Use is subject to Anthropic's Commercial Terms of Service." That is a proprietary license, not an open source one.

The confusion is understandable. The repository is public, and Anthropic does publish open source code around the tool. But the tool you install and run is governed by Anthropic's terms, and the license grants no right to modify or redistribute it.

What the license says

The license file is two sentences long. It reserves all rights and points to the Commercial Terms of Service. Anthropic's legal and compliance page adds which terms apply to you, as of November 1, 2026:

• Team, Enterprise and API users: the Commercial Terms of Service.
• Free, Pro, Max and Ultra users: the Consumer Terms of Service.

The same page sets conditions for companies that want to ship Claude Code inside their own products. The Claude Code binary must not be modified, and it must be installed and run as Anthropic publishes it. Customers may not remove or restrict its sign-in methods, and may not pay for or resell Claude usage on behalf of their end users. You also can't use the Claude Code name or logo as part of your own product name.

Those are not the terms of an open source project, where anyone can fork and change the software.

What is open and what is not

Anthropic's own repositories mix three kinds of license. Here is what each one says, as of November 1, 2026.

"Source-available" means you can read the code but don't get the freedoms of open source. Anthropic uses that phrase itself for the four document skills in its skills repository.

The Agent SDK

The Agent SDK lets you run Claude Code's agent loop and built-in tools from your own Python or TypeScript program. Install it with pip install claude-agent-sdk for Python. The Python package bundles the Claude Code CLI, so you don't install it separately.

The licensing here is mixed. The Python repository includes an MIT license file. Its README and the SDK docs say use of the SDK is governed by Anthropic's Commercial Terms of Service, "except to the extent a specific component or dependency is covered by a different license as indicated in that component's LICENSE file." Treat the Commercial Terms as the rule that applies to you, and read the license file of any component you plan to copy.

The docs also say developers building products on the SDK should use API key authentication. They may not offer claude.ai login for their own apps unless Anthropic has approved it. The branding rules forbid calling your agent "Claude Code".

Plugins and skills

The README for the Claude Code repository says Anthropic's plugins are developed in claude-plugins-official. That repository is licensed Apache-2.0, which is open source. It has a /plugins folder for plugins Anthropic maintains and an /external_plugins folder for partner and community ones. Install from it with /plugin install {plugin-name}@claude-plugins-official.

The README adds that each linked plugin has its own license file, so check before reusing one. It also warns that Anthropic does not control what MCP servers, files or other software a plugin includes.

Skills work the same way. The skills repository says it is for demonstration and educational purposes. Its open and source-available split is described in the table above.

What this means for you

You can use Claude Code freely on your own projects under the terms. You can read, copy and adapt the Apache-2.0 plugins and skills, and the MIT-licensed Python SDK file, within their license files. You cannot fork Claude Code itself, patch it and redistribute it.

If you need a coding agent whose source you can modify, Claude Code is the wrong choice. If you need one you can extend, hooks, plugins, skills, MCP servers and the SDK are all documented routes.

Is Claude Code free?

Open source and free are different questions. Claude Code is not free to use at full strength. Our guide, is Claude Code free, covers the plans in detail. On Anthropic's pricing page as of November 1, 2026, the Free plan does not include Claude Code. Pro costs $20 a month billed monthly, or $17 a month billed annually. Max starts at $100 a month and Ultra is $200 a month. You can also use an Anthropic Console account, billed at API rates.

How to download Claude Code

The native installer is the recommended route. On macOS, Linux or WSL, run curl -fsSL https://claude.ai/install.sh | bash. On Windows PowerShell, run irm https://claude.ai/install.ps1 | iex. Homebrew (brew install --cask claude-code) and WinGet (winget install Anthropic.ClaudeCode) also work, but they don't auto-update. Step-by-step instructions are in our guide on how to install Claude Code, and Anthropic's overview lists every surface.