Question 1

What does JSON to TypeScript do?

Accepted Answer

It generates TypeScript interfaces by inferring field names and types directly from a sample JSON object you paste in.

Question 2

Is my JSON sample uploaded to a server?

Accepted Answer

No — interface generation happens locally in your browser, so you can safely use real API response data without exposing it.

Question 3

Why aren't any fields marked optional (?) in the generated interface?

Accepted Answer

Because types are inferred from a single sample object, the tool has no way of knowing which fields might be missing or null in other responses, so every field is generated as required — you'll need to manually add '?' where your real data actually varies.

Question 4

How does it handle nested objects and arrays?

Accepted Answer

Nested objects typically get their own named sub-interfaces, and arrays are typed based on the shape of their first element, so arrays with mixed-type items may not be represented perfectly.

Question 5

Is this tool free to use?

Accepted Answer

Yes, it's free and requires no account.

Frequently asked questions about JSON to TypeScript

What does JSON to TypeScript do?

Is my JSON sample uploaded to a server?

Why aren't any fields marked optional (?) in the generated interface?

How does it handle nested objects and arrays?

Is this tool free to use?