developers.home-assistant/website/versioned_docs/version-0.72/development_index.md

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Starting with Development	Introduction	version-0.72-development_index	development_index

Home Assistant is built from the ground up to be easily extensible using components. Home Assistant uses Python 3 for the backend and Polymer (Web components) for the frontend.

Home Assistant is open-source and licensed under Apache 2.0. Here are links to the source:

• home-assistant: Python server backend.
• home-assistant-polymer: Polymer UI.

For those new to contributing to open source software, make sure you are familiar with all of the tools and concepts used in Home Assistant before you start.

When contributing Home Assistant code:

• Github
• Pip and Virtual Environments
• Python 3
• Pylint
• Flake8
• Tox
• TravisCl

When contributing 3rd Party code to be used by Home Assistant:

• Publishing your own PyPI package