# Functions

eKuiper has many built-in functions for performing calculations on data.

- [Aggregate Functions](./aggregate_functions.md)
- [Math Functions](./mathematical_functions.md)
- [String Functions](./string_functions.md)
- [Array Functions](./array_functions.md)
- [Object Functions](./object_functions.md)
- [Hashing Functions](./hashing_functions.md)
- [Transform Functions](./transform_functions.md)
- [JSON Functions](./json_functions.md)
- [Date and Time Functions](./datetime_functions.md)
- [Other Functions](./other_functions.md)

- [Analytic Functions](./analytic_functions.md)
- [Multi-Row Functions](./multi_row_functions.md)
- [Multi-Column Functions](./multi_column_functions.md)
- [Window Functions](./window_functions.md)

eKuiper also provides a set of functions though shipped plugins. Users need to install the plugins before using them.

- [Custom Functions](./custom_functions.md)