JSON to Kotlin
Paste JSON and get a Kotlin data class with concise property syntax and nested types. Drop into your Android or JVM project.
JSON in, Kotlin out
Paste a typical JSON payload and the tool emits idiomatic Kotlin types — nested objects each become their own type.
{
"id": 1,
"name": "Alice",
"isActive": true
}Generated Kotlin appears here.
What you'll use this for
Skip the boilerplate. Whenever you have an example JSON payload and need typed code on the other side, paste and generate.
API client models
Generate DTOs for a third-party REST API from a sample response.
Database row types
Model JSON columns or document-store records as native Kotlin types.
Mobile + backend parity
Keep client and server types in sync — both generated from the same JSON.
Fixtures and tests
Turn fixture JSON into typed code for unit tests and integration mocks.
How to convert JSON to Kotlin
Paste your JSON
Drop a valid JSON object into the left editor. Arrays at the root work too — the first element is sampled.
Pick a class name
Default is Root. Use anything PascalCase that fits your domain.
Click Generate
Or leave auto-generate on for live updates as you edit JSON. Runs entirely in your browser.
Copy or download
Copy to clipboard or save as a .kt file ready to drop into your project.
Frequently asked questions
A data class auto-generates equals(), hashCode(), toString(), copy(), and componentN methods — ideal for DTOs.
Yes. Each nested JSON object becomes its own data class with PascalCase naming.
Yes — the output is plain Kotlin. Add @Serializable on each class to use kotlinx.serialization.
Yes. Completely free, no signup, no limits. Runs entirely in your browser.
About JSON to Kotlin
This tool converts a sample JSON payload into idiomatic Kotlin code. Every nested object is recursively turned into its own type with PascalCase naming, while keys are converted to the conventional case for the language.
Type inference
- Strings stay strings.
- Integers use the language's widest safe integer type (e.g.
long,Int,i64). - Decimals become double-precision floats.
- Arrays become a generic list keyed off the first element's type.
- Booleans map to the native boolean type.
- Nested objects recurse into their own type definitions.
Privacy
- All conversion happens locally in your browser.
- No JSON ever leaves your device.
- No signup, no tracking of payloads.