JSON to Kotlin Data Class Converter

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

Key Facts

Category
Developer & Web
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

  • •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.

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.
Example Config
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
Paste the user registration JSON payload, set the Root Type Name to 'UserRegistration', leave 'Nullable Properties' unchecked for strict non-null validation, and copy the output.
Example Config
Root Type Name: UserRegistration, Nullable Properties: False
Outcome
Generates clean, non-nullable Kotlin data classes with nested classes for the address and list types for the roles.

Try with Samples

json
Android Serialization Kotlin Samples
Android Kotlin serialization examples including JSON serialization, deserialization, and XML parsing
title token kotlin
json
Terraform Plan JSON Samples
Sample Terraform plan JSON files exported from terraform show -json style payloads for dependency visualization and change review
title token json
json
Chat Transcript JSON Samples
JSON examples for multi-role chat transcripts
title token json
json
JSON Samples
JSON (JavaScript Object Notation) format examples from simple to complex structures
title token json
json

Related Hubs

JSON Interchange and Format Translation Tools
Compare JSON conversion tools for CSV, YAML, TOML, GraphQL, XML, Markdown, Excel, BSON, EDN, and related structured formats in one hub.
JSON Inspection, Diff, and Transformation Tools
Compare JSON formatting, diffing, path inspection, schema validation, merging, transformation, and export tools in one hub for API and data workflows.
JSON Schema, Mock Data, and API Fixture Generators
Curated tools for JSON schema generation, mock payload building, and API fixture preparation in one hub.
JSON Formatting, Diff, and Normalization Tools
Compare JSON formatting, diffing, log review, config comparison, and data-normalization tools in one hub for readable and reviewable JSON workflows.

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.

API Documentation

Request Endpoint

POST /en/api/tools/json-to-kotlin

Request Parameters

Parameter Name Type Required Description
jsonInput textarea Yes -
rootName text No -
optionalFields checkbox No -

Response Format

{
  "result": "Processed text content",
  "error": "Error message (optional)",
  "message": "Notification message (optional)",
  "metadata": {
    "key": "value"
  }
}
Text: Text

AI MCP Documentation

Add this tool to your MCP server configuration: 

{
  "mcpServers": {
    "elysiatools-json-to-kotlin": {
      "name": "json-to-kotlin",
      "description": "Convert JSON data into Kotlin data classes with @SerializedName annotations, nullable handling, and nested type inference",
      "baseUrl": "https://elysiatools.com/mcp/sse?toolId=json-to-kotlin",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

You can chain multiple tools, e.g.: `https://elysiatools.com/mcp/sse?toolId=png-to-webp,jpg-to-webp,gif-to-webp`, max 20 tools.

If you encounter any issues, please contact us at [email protected]