> ## Documentation Index
> Fetch the complete documentation index at: https://docs.xano.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Building Custom Functions in Xano
> Learn how to build Custom Functions (reusable logic)
Before continuing, make sure you're familiar with:
* [Core Components](/building/logic/core-components)
* [Working with Data](/building/logic/working-with-data)
## Building Custom Functions in Xano
Custom Functions are a way to build reusable logic that you can utilize in other workflows. They allow you to build a set of steps once, use them in multiple places, and maintain them in one place.
Custom Functions in Xano are built in three parts:
* Inputs
\-- Inputs are the data that the Custom Function will accept. For example, `name` and `email`.
* Logic
\-- The logic is the logic that will be executed when the Custom Function is called. For example, retrieving a record from your database or calculating a user's age.
* Response
\-- The response is the data that the Custom Function will return. For our `user_list` Custom Function, it might return a list of users, or a single user.
## Custom Function Folders
You can organize your Custom Functions into folders for better organization by adding a folder name to the Custom Function name -- for example, `utilities/user_list` instead of just `user_list`.
You can select Move functions to move your Custom Functions into a folder, and Add Folder to add a new folder.
## Creating a new Custom Function
From the sidebar, click Functions or hover over it and click to create a new function immediately.
Clicking the **+ Add Function** button will open a panel that allows you to create a new Custom Function.
You'll be asked to provide some basic information about your Custom Function before continuing.
| Parameter | Description |
| --------------- | ----------------------------------------------------------------------------------------------------------- |
| Name | The name of the Custom Function. |
| Description | A description of the Custom Function. |
| Folder Path | The folder path for the Custom Function; this is optional and you don't need to use a folder if you prefer. |
| Tags | Tags for organization. |
| Request History | The request history settings for the Custom Function. |
You can build Custom Functions in Xano in three different ways. Choose the one that best fits your needs. You can switch between them at any time.
## The Canvas View
The canvas view is a visual representation of your custom function in a node-based format. If you're new to the canvas view, review the [Canvas View](/building/build-visually/canvas-view) basics first.
Inputs define the data your custom function expects. Learn how to add and configure them.
Functions define the behavior of your custom function. Add and arrange functions to process inputs and fetch data.
Control exactly what data your custom function sends back.
Inputs define the data your custom function expects. Learn how to add and configure them.
Functions define the behavior of your API. Add and arrange functions to process inputs and fetch data.
Control exactly what data your API sends back.
A basic custom function in XanoScript has three parts — **inputs**, **functions**, and **response** — just like in the visual builder:
```javascript lines icon="code" Example of a basic custom function in XanoScript theme={null}
function utilities/format_timestamp {
description = "Makes a timestamp human readable"
input {
timestamp? timestamp?
}
stack {
var $readable_timestamp {
value = $input.timestamp|format_timestamp:"r":"UTC"
}
}
response {
value = $readable_timestamp
}
middleware = {pre: [], post: []}
}
```
For more information on how to build custom functions in XanoScript, see the XanoScript custom functions documentation.