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## Resource: About Wix Functions APIs

## Article: About Wix Functions APIs

## Article Link: https://dev.wix.com/docs/api-reference/business-management/functions/about-wix-functions-apis.md

## Article Content:

# About Wix Functions APIs

The Wix Functions APIs allow you to manage a site's [Functions](https://support.wix.com/en/wix-functions) through code. 

With the Wix Functions APIs, along with the [Automations API](https://dev.wix.com/docs/api-reference/business-management/automations/introduction.md), you can control every aspect of a site's functions.

## What are Wix Functions?

Wix Functions allow you to create custom business logic that integrates with [Wix's business solutions](https://dev.wix.com/docs/api-reference/articles/work-with-wix-apis/platform/about-apps-created-by-wix.md). Functions run at specific points in a business solution's workflows. Using functions, you can create custom behaviors, validations, and integrations that aren't available by default. For example, adding a fragile packaging fee to a checkout flow.

The simplest way to implement Functions on your site is to use the [**Functions** dashboard page](https://www.wix.com/my-account/site-selector/?buttonText=Select%20Site&title=Select%20a%20Site&autoSelectOnSingleSite=true&actionUrl=https:%2F%2Fwww.wix.com%2Fdashboard%2F%7B%7BmetaSiteId%7D%7D%2Ffunctions/manage). This page allows you to manage your site's functions and their logic through a no-code interface.

## How Functions extend site functionality

Functions work by integrating with existing Wix business solutions through a [service plugin](https://dev.wix.com/docs/api-reference/business-management/functions/about-service-plugins-and-wix-functions.md) architecture. You must build each function from a [function type](#terminology) that a service plugin defines and that specifies the following:
- When the business solution calls the function.
- What parameters the function accepts.
- What the function returns.

Learn more about [function architecture](https://dev.wix.com/docs/api-reference/business-management/functions/function-architecture.md).

## When to use the Functions APIs

In most cases, it's simplest to add functions to a site using the site's dashboard. However, there are some cases when developing an app or a site where you need to use APIs:

- **Apps**: To use functions in an app, you must use the Functions APIs.
- **Sites**: To manage functions dynamically. For example, to activate functions based on site events rather than manually editing the site's **Functions** page.

## Use cases

- [Add a fragile packaging fee from a function template](https://dev.wix.com/docs/api-reference/business-management/functions/sample-flows.md#add-a-fragile-packaging-fee-from-a-function-template-basic-production-flow)
- [Add a custom validation at checkout](https://dev.wix.com/docs/api-reference/business-management/functions/sample-flows.md#add-a-custom-validation-at-checkout-basic-production-flow)
- [Require a minimum number of different items at checkout with a builderless flow](https://dev.wix.com/docs/api-reference/business-management/functions/sample-flows.md#require-a-minimum-number-of-different-items-at-checkout-builderless-production-flow)

## Terminology

- **Business solution**: An app built by Wix, such as Wix Stores.
- **Function**: Logic that runs at a specific point in a Wix business solution's workflows.
- **Function extension**: Another name for a function type.
- **Function method**: An objects that connects logic, defined in an [automation](https://dev.wix.com/docs/api-reference/business-management/automations/introduction.md), to a function.
- **Function type**: A slot for a function within a business solution workflow that defines when the function runs and what data it receives and returns.
- **Function template**: An implementation of a function type with attached logic from which you can create a function.
- **Service plugin**: An interface that defines how a function integrates with a Wix business solution.
- **Service plugin configuration**: Static data that's sent to a business solution when a function runs.
- **SPI**: Service plugin.

## See also
- [Function Architecture](https://dev.wix.com/docs/api-reference/business-management/functions/function-architecture.md)
- [About Function Creation and Activation](https://dev.wix.com/docs/api-reference/business-management/functions/about-function-creation-and-activation.md)
- [About Service Plugins and Wix Functions](https://dev.wix.com/docs/api-reference/business-management/functions/about-service-plugins-and-wix-functions.md)
- [Supported Function Types](https://dev.wix.com/docs/api-reference/business-management/functions/supported-function-types.md)
- [Sample Flows](https://dev.wix.com/docs/api-reference/business-management/functions/sample-flows.md)