JSON to Kotlin Data Class
LiveGenerate Kotlin data class definitions from JSON data.
Understanding JSON (JavaScript Object Notation)
Kotlin is the primary language for Android development and a popular choice for backend JVM applications. Kotlin data classes provide type-safe JSON parsing with libraries like Moshi, Gson, and kotlinx.serialization. Converting JSON to Kotlin data classes generates the boilerplate code needed for JSON deserialization — property declarations, nullable types, default values, and serialization annotations. This is essential for Android API integration, backend data models, and multiplatform Kotlin projects.
Convert JSON data to Kotlin data classes with proper types, nullable annotations, and SerializedName annotations for Gson/Moshi. Handles nested objects, arrays, and generates idiomatic Kotlin code with val properties. Perfect for Android developers building API models.
The Devkitr JSON to Kotlin Data Class Converter generates Kotlin data class definitions from JSON data. Paste JSON to get data classes with val properties, nullable types (String?), default values, nested class definitions, and optional @SerialName annotations for JSON key mapping.
In a typical development workflow, JSON to Kotlin Data Class becomes valuable whenever you need to generate kotlin data class definitions from json data. Whether you are working on a personal side project, maintaining production applications for a company, or collaborating with a distributed team across time zones, having a reliable browser-based conversion tool eliminates the need to install desktop software, write one-off scripts, or send data to third-party services that may log or retain your information. Since JSON to Kotlin Data Class processes everything locally on your device, your data stays private and your workflow stays uninterrupted — open a browser tab, paste your input, get your result.
Key Features
Data Class Generation
Creates Kotlin data classes with val properties, proper types (String, Int, Long, Double, Boolean), and constructor declarations.
Nullable Type Handling
Uses Kotlin nullable types (String?, Int?) for JSON fields that can be null, leveraging Kotlin's null safety system.
Serialization Annotations
Optionally generates @SerialName (kotlinx.serialization), @Json (Moshi), or @SerializedName (Gson) annotations for JSON key mapping.
Nested Data Classes
Creates separate data class definitions for nested JSON objects with properly typed property references.
How to Use JSON to Kotlin Data Class
Paste JSON Data
Enter JSON from your API, configuration, or any source you need to parse in Kotlin.
Select Serialization Library
Choose your serialization library (kotlinx.serialization, Moshi, Gson) for the correct annotation format.
Review Data Classes
Check property names, types, nullable annotations, and nested class definitions.
Copy Kotlin Code
Copy the data classes into your Kotlin project for type-safe JSON parsing.
Use Cases
Android API Integration
Generate data classes for Retrofit response parsing with Kotlin type safety and null checking.
Ktor Client Response Types
Create data classes for Ktor HTTP client JSON deserialization in Kotlin backend and multiplatform projects.
Firebase Data Mapping
Generate Kotlin data classes matching Firebase Realtime Database or Firestore document shapes for type-safe data access.
Spring Boot DTOs
Create Kotlin data classes for Spring Boot REST API request and response DTOs with Jackson annotations.
Pro Tips
Use val (immutable) for data class properties unless you specifically need mutable state — immutability prevents accidental data modification.
Add default values (= null, = emptyList()) to optional properties for flexible deserialization when JSON responses omit certain fields.
Choose kotlinx.serialization for Kotlin Multiplatform projects and Moshi for Android-only projects — Gson is legacy but still widely used.
Consider using sealed classes for JSON fields that can contain different object types based on a discriminator field.
Common Pitfalls
Using platform types (Java types without null annotations) instead of Kotlin nullable types
Fix: Explicitly declare properties as String? for nullable JSON fields. Platform types bypass Kotlin null safety and cause runtime NullPointerExceptions.
Not including a no-argument constructor for Jackson/Gson deserialization
Fix: Add default values to all properties or use the jackson-module-kotlin/gson-kotlin-adapter for proper Kotlin data class deserialization without no-arg constructors.
Generating List instead of List for array fields that could be absent
Fix: Use List<T> = emptyList() for array fields that may be missing from the JSON response, preventing null pointer exceptions.
Frequently Asked Questions
QDoes it add @SerializedName annotations?
Yes. You can toggle Gson @SerializedName or Moshi @Json annotations for property name mapping.
QAre nullable types handled?
Yes. JSON null values generate nullable Kotlin types (String?) with proper defaults.
QDoes it work for Android development?
Yes. The generated data classes are fully compatible with Retrofit, Gson, Moshi, and Kotlin Serialization.
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