JSON to TypeScript, Java, Go & Python

Paste a JSON response and get ready-to-use type definitions. Nested objects become their own named types, and fields missing from some array items become optional.

Root type name

JSON

TypeScript

How types are inferred

Nested objects become separate types named after their key in PascalCase, so "shippingAddress": {…} becomes ShippingAddress.
Arrays of objects are merged: every item is inspected, and a field that's missing from some items is marked optional. Plural keys are singularised, so "orderItems" becomes a list of OrderItem.
Numbers become integers when every sample is a whole number, and floating point otherwise.
null values make a field nullable. A field that's always null gets a catch-all type, because there's nothing to infer from.

What each language gets

TypeScript: exported interfaces, with ? for optional fields and | null for nullable ones.
Java: records (Java 16+). Keys that aren't valid Java names get a Jackson @JsonProperty annotation.
Go: structs with json tags, omitempty for optional fields and pointers for nullable ones.
Python: dataclasses with type hints. Optional fields default to None.

Check the result

The types are only as good as the sample. If your JSON has one item where an API usually returns many, some optional fields can look required. Paste a response with several items for the most accurate result.