JSON → TypeScript

Convert a JSON sample into TypeScript interface definitions instantly, entirely in your browser.

Usage

Paste any valid JSON into the left panel. TypeScript interfaces are generated immediately in the right panel.

Options

  • Root name — sets the name of the top-level interface (default: Root).
  • Optional fields — when enabled, all fields get a ? modifier (e.g. name?: string).

How it works

  • Nested objects each become their own named interface, named after the parent key in PascalCase.
  • Arrays of objects derive their element interface name by dropping a trailing s from the key (e.g. Users → User); if the name has no trailing s, Item is appended (e.g. Root → RootItem).
  • Mixed-type arrays produce a union type, e.g. (string | number)[].
  • Empty arrays produce unknown[].
  • Keys containing special characters are automatically quoted.
  • When the root value is an array of objects, element interfaces are emitted followed by a type alias for the root name (e.g. type Users = User[];). When the root is a primitive array, only the type alias is emitted.
  • Duplicate interface names get a numeric suffix (Root2, Root3, …).

Every change is written to the URL as a ?v= parameter. Share or bookmark the URL to restore the full state.