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How to Convert Kotlin to JSON - Step by Step Guide

Step 1

Input Your Kotlin Code

Start by pasting your Kotlin data class, map, or list that needs to be converted to JSON format. The tool supports data class initialization, mapOf, listOf, and nested structures.

Paste Kotlin code: Copy your Kotlin data class or collection directly into the editor
Upload a file: Load Kotlin code from a .kt file on your computer
Try samples: Click sample buttons to see different Kotlin patterns (data classes, lists, maps, nested structures)

Example: Kotlin Data Class

Here's a typical Kotlin data class:

Person(
    name = "Emma Wilson",
    age = 27,
    isActive = true,
    skills = listOf("Kotlin", "Android", "Jetpack Compose")
)
Step 2

Click Convert Button

Click the green "Convert" button to send your Kotlin code to our Python backend API for processing. The converter transforms Kotlin syntax to JSON format, handling true/false, null values, lists, and proper quote formatting.

Boolean conversion: Kotlin true/false becomes JSON true/false
Null handling: Kotlin null converts to JSON null
Collection support: Kotlin listOf/mapOf convert to JSON arrays/objects
Named parameters: Kotlin parameter names become JSON keys
Nested structures: Handle complex Kotlin data class hierarchies

Example: Converted JSON Output

The same data in JSON format:

{
  "name": "Emma Wilson",
  "age": 27,
  "isActive": true,
  "skills": [
    "Kotlin",
    "Android",
    "Jetpack Compose"
  ]
}
Step 3

Get Valid JSON Output

The tool produces properly formatted, valid JSON that's ready to use in your applications, APIs, or configurations.

Real-time validation: Green checkmark confirms your JSON is syntactically correct
Proper formatting: Beautified with correct indentation and structure
Ready for APIs: Use directly in REST API responses or database storage
Step 4

Copy or Download JSON

Copy the JSON to your clipboard or download it as a .json file for use in your Kotlin or Android projects.

Copy to clipboard for immediate use
Download .json file for integration into your codebase
Use in Android: Perfect for Retrofit, Room, and kotlinx.serialization
Export options: Convert to readable tables or minify for production

What is Kotlin to JSON Conversion?

Kotlin to JSON conversion transforms Kotlin data structures like data classes, maps, and lists into standard JSON format. This process converts Kotlin-specific syntax (data class parameters, listOf, mapOf) into JSON-compliant syntax for data interchange and API communication.

The conversion is essential for Android applications, backend services, and configuration management where JSON is the standard format for data exchange. You can also convert other languages like Java to JSON or Python to JSON using our related tools.

Frequently Asked Questions

How do I convert Kotlin data class to JSON?

Simply paste your Kotlin data class initialization into the converter. It will automatically convert Kotlin syntax (named parameters, true, false, null, listOf, mapOf) to valid JSON format. The output can then be formatted or minified based on your needs.

Does the converter handle nested Kotlin data classes?

Yes! The converter properly handles nested data classes, lists, maps, and mixed data structures, converting them to equivalent JSON representations while maintaining the structure. You can also convert the reverse direction using our JSON to Kotlin converter.

What Kotlin data types are supported?

The converter supports Kotlin data classes, lists (listOf, mutableListOf), maps (mapOf, mutableMapOf), strings, numbers, booleans (true/false), and null. These are converted to their JSON equivalents: objects, arrays, strings, numbers, booleans, and null.

Is the output valid JSON?

Yes! The converter produces standard, valid JSON that can be used in any application or API. The output is properly formatted and validated. You can further validate the JSON or convert it to other formats like TypeScript or Python.

Is the Kotlin to JSON converter free?

Yes, completely free with no limitations on data size or conversion frequency. No registration required. Check out our other free tools like JSON formatter, JSON validator, and JSON to Table converter.