# Is the Claude Agent SDK open source?

Only the Python package. `claude-agent-sdk-python` ships under the MIT license, copyright Anthropic PBC, so its source is public, modifiable, and redistributable. The TypeScript package, `claude-agent-sdk-typescript`, isn't: its `LICENSE.md` says "All rights reserved," with use governed by Anthropic's Commercial Terms of Service, the same terms Anthropic's own SDK overview says govern the Agent SDK generally, "except to the extent a specific component or dependency is covered by a different license as indicated in that component's LICENSE file." The Python package is that exception, not the rule. Either way, what the SDK wraps, [the tool-calling loop](/answers/tool-calling/what-is-tool-calling) that runs against the Claude Code binary, is unaffected by which license the wrapper carries; open or not, it still calls the Claude API and bills like any other Claude usage.

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Sources:
- claude-agent-sdk-python, LICENSE: https://github.com/anthropics/claude-agent-sdk-python/blob/main/LICENSE (fetched 2026-10-01)
- claude-agent-sdk-typescript, LICENSE.md: https://github.com/anthropics/claude-agent-sdk-typescript/blob/main/LICENSE.md (fetched 2026-10-01)
- Agent SDK overview, Anthropic: https://code.claude.com/docs/en/agent-sdk/overview (fetched 2026-10-01)

Source: https://tessary.ai/answers/claude-agent-sdk-evals/is-the-claude-agent-sdk-open-source
More on Claude agent sdk evals: https://tessary.ai/answers/claude-agent-sdk-evals
From Tessary, agent reliability for AI agents in production: https://tessary.ai