How to use the JSON to Kotlin
- Paste your JSON into the input box, or open a file.
- Adjust the options if needed. The output updates as you type.
- Copy the Kotlin or download it as a file.
About JSON
JSON (JavaScript Object Notation) is the default data format of web APIs, package manifests and most configuration tooling. It supports objects, arrays, strings, numbers, booleans and null.
How it works
Nested objects become their own data classes, arrays of objects are merged so every key is covered, and fields that are missing or null in some items are marked optional.
Private by design
Developer data is often sensitive: API responses, tokens, customer records, internal configs. This JSON to Kotlin processes everything locally in your browser tab. There is no server round-trip, no logging and no storage of your input.
Frequently asked questions
Is this JSON to Kotlin free?
Yes. This JSON to Kotlin is completely free to use with no sign-up, no limits and no ads inside the tool.
Is my data uploaded to a server?
No. The JSON to Kotlin runs entirely in your browser using JavaScript. Nothing you paste is sent to DevT Pro or any other server.
How are Kotlin types inferred?
Nested objects become their own data classes, arrays of objects are merged so every key is covered, and fields that are missing or null in some items are marked optional.
Can I use the JSON to Kotlin offline?
Yes. JSON to Kotlin is also built into DevT Pro, a native app for Mac, Windows, iPad and Linux with 120+ developer tools that work fully offline. It is a $5.99 one-time purchase with no subscription.
