# JSON to Kotlin Data Class Converter

Convert JSON data into Kotlin data classes with @SerializedName annotations, nullable handling, and nested type inference

> Canonical page: https://elysiatools.com/en/tools/json-to-kotlin

- **Category:** Development

- **Keywords:** json, kotlin, data class, convert, transform, codegen, json to kotlin, SerializedName, gson, moshi, dto

## Overview

The JSON to Kotlin Data Class Converter simplifies Android and backend development by instantly generating clean, type-safe Kotlin data classes from raw JSON payloads. It automatically infers nested object structures, handles arrays, generates @SerializedName annotations for serialization libraries, and supports nullable property configurations.

## Inputs

- **JSON Input** (textarea): { "name": "Alice", "age": 30, "roles": \["admin", "user"\], "address": { "city": "Shanghai", "zip": "200000" } }
- **Root Type Name** (text): Root
- **Nullable Properties** (checkbox)

## When to use

- When integrating a new REST API and you need to quickly generate Kotlin Data Transfer Objects (DTOs) from JSON response payloads.
- When migrating legacy Java models or manual JSON parsing code to clean, idiomatic Kotlin data classes.
- When configuring serialization models that require custom field mapping annotations alongside nullable property definitions.

## How it works

- Paste your raw JSON payload into the JSON Input text area.
- Specify the Root Type Name and toggle the Nullable Properties option if your API fields can be null.
- Copy the generated Kotlin code, complete with nested classes and @SerializedName annotations, directly into your project.

## Use cases

- Generating Retrofit API response models for Android application development.
- Creating Kotlin DTOs for Spring Boot or Ktor backend services consuming external JSON APIs.
- Rapidly prototyping data structures during initial API design phases.

## Frequently asked questions

### Does this tool support nested JSON objects?

Yes, it automatically detects nested objects and generates corresponding nested Kotlin data classes.

### How does the tool handle JSON arrays?

It infers the item type within the array and represents it as a Kotlin List of that type.

### Can I make all generated properties nullable?

Yes, checking the Nullable Properties option will append a question mark to all property types, making them nullable.

### What annotations are added to the generated Kotlin classes?

The tool generates @SerializedName annotations for each property to ensure compatibility with serialization libraries like Gson.

### Do I need to define names for nested classes manually?

No, the converter automatically infers appropriate class names for nested objects based on their JSON key names.

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## Samples

- [Android Serialization Kotlin Samples](https://elysiatools.com/en/samples/android-serialization-kotlin): Android Kotlin serialization examples including JSON serialization, deserialization, and XML parsing
- [Terraform Plan JSON Samples](https://elysiatools.com/en/samples/terraform-plan-json-samples): Sample Terraform plan JSON files exported from terraform show -json style payloads for dependency visualization and change review
- [Chat Transcript JSON Samples](https://elysiatools.com/en/samples/chat-transcript-json): JSON examples for multi-role chat transcripts
- [JSON Samples](https://elysiatools.com/en/samples/json): JSON (JavaScript Object Notation) format examples from simple to complex structures

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