Paste JSON and get TypeScript interfaces instantly
Paste JSON. Generates matching TypeScript interfaces with proper types. Copy and use.
Manual interface writing is tedious. Auto-infer types from JSON data.
Numbers, strings, booleans, nested objects, arrays.
Yes, separate interfaces for nested objects.
Yes, marks inconsistent properties.
Customize root interface name.
TypeScript brings compile-time type safety to JavaScript. When you have JSON data from an API, you need TypeScript types (interfaces or types) to use it safely in TypeScript code. Manually writing types from JSON is error-prone: a single missed field causes runtime bugs that TypeScript would have caught at compile time. This tool reads your JSON structure and generates matching TypeScript interfaces, including nested objects and arrays.
TypeScript has two syntaxes for defining types: interface (declaration syntax) and type (alias syntax). Interfaces support declaration merging (you can add fields later), are extendable with extends, and are generally preferred for object shapes. Types support unions, intersections, and computed types — features interfaces don't. Most style guides recommend interface for data shapes and type for unions. Our converter outputs interface by default.
For nested objects (an object containing other objects), the tool generates separate interfaces for each level. For arrays of objects, it creates an array type like User[]. For optional fields (those that appear in some objects but not others), it adds ? to mark them optional. The output is a complete, copy-pasteable TypeScript file you can drop into your project.
Convert JSON objects to TypeScript interfaces automatically with the Toolzie JSON to TypeScript converter. Paste any JSON and get a fully typed TypeScript interface in seconds — a huge time-saver for TypeScript developers.
Yes — nested JSON objects generate nested TypeScript interfaces automatically.
Arrays are typed as the appropriate array type, e.g. string[] or User[].
Null values are typed as the detected type unioned with null, e.g. string | null.
Yes — the generated interfaces are valid TypeScript and can be pasted directly into your .ts or .d.ts files.