JSON to Kotlin Data Class Converter

JSON to Kotlin Data Class Converter | Online Free Tool | Elysia Tools

Tool usage guide

Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Category: Development
Input types: textarea, text, checkbox
Output type: text
Sample coverage: 4
API ready: Yes

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.

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

1Paste your raw JSON payload into the JSON Input text area.
2Specify the Root Type Name and toggle the Nullable Properties option if your API fields can be null.
3Copy 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.

Examples

1. Generating Android API Response Models

Android Developer

Background

An Android developer is integrating a third-party weather API that returns a complex nested JSON structure.

Problem

Manually writing Kotlin data classes for a nested JSON response with dozens of fields is time-consuming and error-prone.

How to use

Paste the weather API JSON response into the input, set the Root Type Name to 'WeatherResponse', check the 'Nullable Properties' option to handle missing fields safely, and generate the code.

Root Type Name: WeatherResponse, Nullable Properties: True

Outcome

Instantly generates a set of Kotlin data classes with @SerializedName annotations and nullable types, ready to be used directly with Retrofit.

2. Creating Backend DTOs for User Profiles

Kotlin Backend Engineer

Background

A backend engineer using Ktor needs to parse incoming user registration payloads containing nested address and role arrays.

Problem

Needs to quickly create non-nullable Kotlin data classes that match the incoming JSON structure exactly.

How to use

FAQ

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.

Root Type Name: UserRegistration, Nullable Properties: False

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Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Overview

When to use

How it works

Use cases

Examples

1. Generating Android API Response Models

2. Creating Backend DTOs for User Profiles

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