🧬 JSON → Type Definition Converter

Paste JSON and instantly generate TypeScript, PHP, Python, Go, and Rust type definitions. Handles nested objects and arrays.

✅ 100% free, no signup, runs entirely in your browser

JSON Input

💡 Tips

• Nested objects are automatically extracted as separate types.

• Array element types are inferred. Empty arrays become any[] / []interface{} etc.

• null is treated as optional / nullable like string | null.

• Change the root type name from the input above.

1

Enter or paste JSON

Paste JSON into the left input field. Use the Sample button to quickly load example data.
2

Select target language

Choose TypeScript, PHP, Python, Go, Rust, Kotlin, or Swift, and optionally change the root type name.
3

Copy and use the type definition

The generated type definition appears on the right. Copy it to your clipboard and paste it into your code.

How are nested objects handled?

Nested objects are automatically extracted as separate type definitions and referenced by name.

How are null fields typed?

null fields are treated as optional/nullable. Depending on the language they become Optional, ?, pointer type, etc.

Does it handle a top-level JSON array?

Yes. If the root is an array, it is automatically wrapped as { items: [...] } for type generation.