JSON to TypeScript Interface
Paste JSON and TypeScript interfaces are generated live. Nested objects split into their own interfaces; arrays, nulls, and mixed types are inferred precisely.
How to Use
Paste JSON on the left — single object, array, or nested structure. Parse errors show the offending position.
Set the root interface name, force all fields optional, sort keys, and more.
TypeScript interfaces appear live on the right. One click copies them, ready to paste into a .ts file.
FAQ
How are nested objects handled?
Each nested object becomes its own interface. The name comes from the parent key, PascalCased. e.g., `user.address` → an `Address` interface.
How are array types inferred?
Items are scanned: a single type yields `T[]`, mixed yields `(A | B)[]`. Object arrays use the first item as the schema, and missing keys across items become optional (`?`).
What about null fields?
Fields seen only as `null` get the `null` type. Mixed values produce unions like `string | null`. Toggling "All fields optional" also adds `?` markers.
When keys aren't valid identifiers?
Keys with hyphens or special characters are auto-quoted. e.g., `"my-key": string`.
Is anything sent to a server?
No. All conversion runs in your browser; nothing leaves the page.
