> For the complete documentation index, see [llms.txt](https://v2.dataos.info/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://v2.dataos.info/concepts/resources/nilus/batch/custom-sources.md).

# Custom Sources

Custom sources are escape hatches for systems that do not fit a released first-party connector. Use them when a source can be reached through a custom SQL query or a user-authored connector implementation.

## Published Custom Source Paths

| Source                                                                                                   | Category         | Notes                                                                            |
| -------------------------------------------------------------------------------------------------------- | ---------------- | -------------------------------------------------------------------------------- |
| [Custom Query (SQL Sources)](/concepts/resources/nilus/batch/custom-sources/custom-query-sql-sources.md) | Custom SQL       | Read from a SQL-compatible source with a hand-authored query.                    |
| [Custom Source](/concepts/resources/nilus/batch/custom-sources/creating-custom-source.md)                | Custom connector | Build a user-authored Python source when Nilus does not ship a native connector. |

## When to use these paths

Use [Custom Query (SQL Sources)](/concepts/resources/nilus/batch/custom-sources/custom-query-sql-sources.md) first when the source is SQL-compatible and the requirement can be expressed as a controlled query. Use [Custom Source](/concepts/resources/nilus/batch/custom-sources/creating-custom-source.md) only when a first-party connector or SQL query path cannot model the source.


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