> Portal Navigation:
> 
> - Append `.md` to any URL under `https://dev.wix.com/docs/` to get its markdown version.
> - Pages are either content pages (article or reference text) or menu pages (a list of links to child pages).
> - To get a menu page, truncate any URL to a parent path and append `.md` (e.g. `https://dev.wix.com/docs/sdk.md`, `https://dev.wix.com/docs/sdk/core-modules.md`).
> - Top-level index of all portals: https://dev.wix.com/docs/llms.txt
> - Full concatenated docs: https://dev.wix.com/docs/llms-full.txt

## Resource: Introduction

## Article: Introduction

## Article Link: https://dev.wix.com/docs/api-reference/app-management/app-billing/introduction.md

## Article Content:

# About the App Billing APIs

The App Billing APIs include various aspects, such as [billing](https://dev.wix.com/docs/rest/app-management/app-billing/billing/introduction.md), [pricing plans](https://dev.wix.com/docs/rest/app-management/app-billing/app-plans/introduction.md), and [custom charges](https://dev.wix.com/docs/rest/app-management/app-billing/custom-charges-service-plugin/introduction.md). These features allow you to charge site owners for using your app, get information about the pricing plans an app offers, and manage what customers must pay to use your app.  

With the App Billing APIs you can:
+ Retrieve data about a site's [previous paid plans for your app](https://dev.wix.com/docs/rest/app-management/app-billing/billing/get-purchase-history.md).
+ [Redirect site owners to the standard Wix checkout page](https://dev.wix.com/docs/rest/app-management/app-billing/billing/get-url.md) in case you manage your app's pricing page outside of Wix.
+ Retrieve [pricing information for a list of apps](https://dev.wix.com/docs/rest/app-management/app-billing/app-plans/list-app-plans-by-app-id.md).
+ [Add your app's charges](https://dev.wix.com/docs/rest/app-management/app-billing/custom-charges-service-plugin/introduction.md) to the invoice that Wix sends to site owners.
+ [Receive notifications about charges](https://dev.wix.com/docs/rest/app-management/app-billing/custom-charges-service-plugin/charges-rejected-event.md) that Wix doesn't accept, created invoices, or when customers increase their charge limit.
+ Keep your customers informed about [how much your app would charge them if Wix were to send an invoice at this moment](https://dev.wix.com/docs/rest/app-management/app-billing/custom-charges-service-plugin/list-charges.md).


## Terminology

- **App instance**: Specific occurrence of your app on a particular Wix site.
- **Charge**: Price for using your app that you can add to an invoice. You can add up to 5 charges per invoice.
- **Charge limit**: Maximum amount that you're allowed to charge customers for using your app per billing cycle. It helps ensure that customers are aware of their potential costs upfront.
- **Paid plan**: A version of your app that isn't free. This version could require a single one-time payment or a subscription based payment.
- **App plan**: Pricing plan that describes how your app charges users. You can set up multiple plans for your app, with different plans offering different tiers of functionality. For example, you can offer a free plan and 3 paid plans with an increasing number of benefits.
- **Wix pricing page**: Wix offers your app an out-of-the-box pricing page that displays up to 4 app plans for your app to users.
- **Wix checkout**: Wix allows you to charge site owners either through the Wix Billing ecosystem or to manage your app's billing externally. In case you manage your app's pricing page on your own servers, you can still redirect site owners to the standard Wix checkout page by using `getUrl()`.