Is my JSON data uploaded to a server?

No. The conversion runs entirely in your browser with JavaScript. Nothing is sent over the network, which makes the tool safe for sensitive data.

Which Kotlin types are used?

Properties are declared as val, numbers map to Long or Double, and arrays become List . Each nested object becomes its own data class.

What about keys with dashes or other special characters?

Exotic keys are preserved exactly as they appear in the JSON, wrapped in backticks, without any renaming.

JSON to Kotlin Data Class Converter

JSON to Kotlin Data Class Converter — Free Online Tool

Convert JSON to Kotlin data classes instantly in your browser. Free, private and offline-friendly: your data never leaves your device.

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Root name

JSON input

Kotlin output

Why convert JSON to Kotlin?

Writing Kotlin data classes for every API response by hand is slow and error-prone. Paste a sample JSON document above and get ready-to-use data classes in milliseconds, including nested objects and arrays.

How it works

The converter parses your JSON locally and generates Kotlin data classes with val properties. Integers map to Long, floats to Double, and arrays to List<T>. Keys with dashes or other exotic characters are kept unchanged between backticks, so the generated code stays faithful to your payload.

Frequently asked questions

Is my JSON data uploaded to a server?: No. The conversion runs entirely in your browser with JavaScript. Nothing is sent over the network, which makes the tool safe for sensitive data.
Which Kotlin types are used?: Properties are declared as val, numbers map to Long or Double, and arrays become List<T>. Each nested object becomes its own data class.
What about keys with dashes or other special characters?: Exotic keys are preserved exactly as they appear in the JSON, wrapped in backticks, without any renaming.