Paste JSON and generate ready-to-use type definitions in TypeScript, Python, Go, Rust, Java, Kotlin, Swift, C#, Dart or PHP. Nested objects become named types automatically — no sign-up, everything runs in your browser.
// Your code appears here
Related tools
This page replaces the individual converters below, which remain available as standalone pages.
Your JSON is analyzed into a type tree: objects become named interfaces, classes or structs, arrays become typed lists, and primitives map to each language's native types. Nested objects are extracted as separate named types so the output compiles cleanly. Null values produce nullable or optional fields where the language supports them.
What you get per language
TypeScript interfaces, Python dataclasses, Go structs with json tags, Rust structs with serde derives, Java classes with getters and setters, Kotlin data classes, Swift Codable structs, C# classes with JSON property names, Dart classes with fromJson factories, and PHP typed classes. Rename the root type to match your codebase before generating.
No. Parsing and code generation run entirely in your browser with vanilla JavaScript.
How are nested objects handled?
Each nested object becomes its own named type, derived from its key (for example address becomes Address). Arrays of objects reuse the same inferred item type.
What happens with null values?
Fields that are null become nullable or optional in languages that support it (TypeScript | null, Python Optional, Rust Option, Kotlin ?, and so on).
Can I change the root type name?
Yes. Edit the Root type name field before generating and all references update accordingly.
Does it handle arrays of mixed types?
Arrays are typed from the first non-null item. Heterogeneous arrays fall back to the language's generic type (any, Any, object, dynamic).