# ESMValCore

> ESMValCore is the core of ESMValTool: it finds, fixes, and preprocesses Earth system model data according to a YAML recipe and runs diagnostic scripts.


2026, ESMValTool Development Team

## Pages in this subsection

- [Development](index.html.md): To get started developing, have a look at our
- [Preprocessor function](preprocessor_function.html.md): Preprocessor functions are located in `esmvalcore.preprocessor`.
- [Fixing data](fixing_data.html.md): The baseline case for ESMValCore input data is fully CMOR compliant
- [Deriving a variable](derivation.html.md): The variable derivation preprocessor module allows to derive variables which are

## Optional

- [Top-level llms.txt](../llms.txt): Complete documentation index.