# Custom integration

> An integration that is not part of Home Assistant Core, installed by the user in the `custom_components` folder.

Source: https://contributors.home-assistant.io/glossary/custom-integration/

- In code: `custom_components/`
- Also: custom integrations, custom component

Anyone can write a custom integration, and it works like any other integration. The project does not review them, and changes in Home Assistant Core can break them, which is why backward-incompatible changes for developers are announced on the blog.

A custom integration needs a `version` in its manifest. Users find and install many of them through the [Marketplace](https://contributors.home-assistant.io/glossary/marketplace/), built into Home Assistant starting with 2026.11. Before that, the Marketplace was [HACS](https://contributors.home-assistant.io/glossary/hacs/), a custom integration itself. To publish one, see [custom integrations](https://contributors.home-assistant.io/marketplace/guides/integrations/) in the Marketplace area. It is also the recommended way to start a new integration, see [does it belong in core](https://contributors.home-assistant.io/core/integrations/create/#does-it-belong-in-core).

## Related terms

- [Integration](https://contributors.home-assistant.io/glossary/integration/): A package of code that connects Home Assistant to a device, service, or protocol, or adds a feature like automations.
- [Backward-incompatible change](https://contributors.home-assistant.io/glossary/backward-incompatible-change/): A change that requires users or developers to change something on their side, like their configuration or their custom integration.
- [Custom card](https://contributors.home-assistant.io/glossary/custom-card/): A card that is not part of the frontend, loaded by the user from a JavaScript file.
- [Marketplace](https://contributors.home-assistant.io/glossary/marketplace/): The place in Home Assistant where users find and install community-made custom integrations, dashboard cards, themes, and template macros. Built in starting with 2026.11.