> For the complete documentation index, see [llms.txt](https://docs.hackle.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.hackle.io/en/event-management/properties/custom-property.md).

# Custom Property

This document covers Custom Properties that you can define and collect according to your needs.

> 📘 To use Custom Properties
>
> 1. SDK integration is required. (Code work needed!)
>
> 2. The SDKs that support Custom Properties are as follows:
>
> * Android
> * iOS
> * JavaScript
> * React
> * React Native
> * Java/Kotlin
> * Python
> * Node.js

## Design Rules

Apply the following rules when designing Custom Properties.

1. The subjects that can have properties assigned are users.
2. A user can have up to 64 properties.
3. Property values must be expressible as yes/no, number, or string.
4. For property values, numbers can have up to 15 integer digits and 6 decimal places, and strings can be up to 64 characters.

## How to Use

1. **Hackle SDK integration is required.**\
   Check the SDK integration method for the language that supports Custom Properties in the SDK category.
2. **Send to Hackle using the method that accepts a user object as a parameter.**\
   Refer to the `User Identifier & Properties` document for each language in the SDK category.

## Reference documents for developers

| Language     | SDK Integration                                                                      | User Identifier & Properties                                                                                     |
| ------------ | ------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------------------------------- |
| Android      | \[Android SDK Integration]\(../../개발자 문서/android/android-sdk-init.md)                | \[User Identifier & Properties for Android SDK]\(../../개발자 문서/android/android-user-info/index.md)                |
| iOS          | \[iOS SDK Integration]\(../../개발자 문서/ios/ios-sdk-init.md)                            | \[User Identifier & Properties for iOS SDK]\(../../개발자 문서/ios/ios-user-info/index.md)                            |
| JavaScript   | \[JavaScript SDK Integration]\(../../개발자 문서/javascript/js-sdk-init.md)               | \[User Identifier & Properties for JavaScript SDK]\(../../개발자 문서/javascript/js-user-info/index.md)               |
| React        | \[React SDK Integration]\(../../개발자 문서/react/react-sdk-init.md)                      | \[User Identifier & Properties for React SDK]\(../../개발자 문서/react/react-user-info/index.md)                      |
| React Native | \[React Native SDK Integration]\(../../개발자 문서/react-native/react-native-sdk-init.md) | \[User Identifier & Properties for React Native SDK]\(../../개발자 문서/react-native/react-native-user-info/index.md) |
| Java/Kotlin  | \[Java/Kotlin SDK Integration]\(../../개발자 문서/java-kotlin/java-sdk-init.md)           | \[User Identifier & Properties for Java/Kotlin SDK]\(../../개발자 문서/java-kotlin/java-user-info/index.md)           |
| Python       | \[Python SDK Integration]\(../../개발자 문서/python/python-sdk-init/index.md)             | \[User Identifier & Properties for Python SDK]\(../../개발자 문서/python/python-user-info.md)                         |
| Node.js      | \[Node.js SDK Integration]\(../../개발자 문서/node-js/node-sdk-init.md)                   | \[User Identifier & Properties for Node.js SDK]\(../../개발자 문서/node-js/node-user-info/index.md)                   |


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