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Online JSON to Kotlin Data Class Converter

Convert JSON payloads into Kotlin @Serializable data classes with kotlinx.serialization annotations — 100% client-side.

⛶ Launch Fullscreen IDE Use Embedded Editor ↓
Instant Live Conversion (Local)
Input Data24 lines • 478 chars
Converted Output44 lines • 1023 chars

How It Works

Fast, secure, browser-native JSON processing in 3 simple steps

1

Paste JSON Data

Paste your REST API payload or mock JSON into the input editor.

2

Review Generated Kotlin

Inspect the generated @Serializable data classes with @SerialName annotations.

3

Copy to Android Studio

Click "Copy Code" or download UserSession.kt directly into your Android or KMP project.

Idiomatic Kotlin Data Classes for Android & Multiplatform (KMP)

Kotlin has become the primary language for modern Android development and cross-platform mobile engineering with Kotlin Multiplatform (KMP). When integrating REST APIs, developers need strongly typed data models that respect Kotlin's strict null-safety guarantees and integrate smoothly with kotlinx.serialization or Moshi.

JSONForge's JSON to Kotlin Converter inspects your JSON payloads locally and produces clean, idiomatic @Serializable data class definitions. It automatically assigns @SerialName annotations to maintain wire-format compatibility, handles nested structures as standalone child data classes, and sets default null values for optional properties.

📱 Android & KMP Ready

Generates code compatible with kotlinx.serialization, Ktor Client, and Android Jetpack Compose state holders.

🛡️ Strict Null Safety

Null and missing fields are typed with optional question marks (String? = null) to prevent runtime crashes.

🔒 Local Privacy Sandbox

All processing runs in browser memory. Never risk leaking sensitive API credentials, telemetry, or user tokens.

Example: Deserializing JSON in Kotlin with kotlinx.serialization

Here is how to decode a JSON string into the generated Kotlin data class using the official kotlinx.serialization library:

Example: Kotlin Deserialization Snippet

import kotlinx.serialization.json.Json

val jsonString = """{"profileId":"kt_user_7718","handle":"sarah","isOnline":true}"""

// Configure JSON decoder
val format = Json { 
    ignoreUnknownKeys = true 
    isLenient = true
}

// Parse string directly into data class
val userProfile = format.decodeFromString<Root>(jsonString)
println("Logged in user: ${userProfile.handle}, Online status: ${userProfile.isOnline}")

Frequently Asked Questions

Everything you need to know about JSON validation, formatting, and privacy

Our analyzer inspects your JSON keys and values, producing @Serializable data classes with @SerialName("exact_json_key") annotations. This allows your Kotlin code to follow clean camelCase property naming while preserving exact JSON wire-format compatibility.

Related Developer Tools

JSON Viewer & Explorer →

Interactive hierarchical tree and table viewer.

JSON Formatter →

Beautify and indent messy JSON data.

JSON Validator →

Find and fix syntax errors with line/column markers.

JSON Health Score →

0–100 quality score and anomaly detection.

Structural Diff Lab →

Compare two JSON documents structurally.

JSON Minifier →

Compress whitespace for production payloads.