JSON to TypeScript

Overview

Hand-writing TypeScript types for an API response is tedious and error-prone. A JSON-to-TS converter reads a sample JSON object and infers a matching set of interfaces — field names, types, nesting and arrays — so you get accurate types in seconds. It runs entirely in your browser, so your JSON never leaves your machine, which matters when the sample contains anything sensitive.

How to Use (Step by Step)

1. 1

   Paste your JSON

   Drop in a representative JSON object — ideally one that includes every field you expect.

2. 2

   Review the generated interfaces

   The tool infers types and nested interfaces from the structure and displays them.

3. 3

   Copy into your code

   Paste the interfaces into your project and adjust any types the sample couldn't fully determine.

How It Works

You paste a JSON object and the tool walks its structure, mapping each value to a TypeScript type: strings, numbers and booleans to primitives, objects to nested interfaces, and arrays to typed arrays. It names interfaces from their keys and outputs ready-to-paste type definitions you can drop straight into your codebase.

When to Use This

Typing an API response you're integrating. Turning a config or fixture file into strict types. Scaffolding models from a sample payload. Keeping front-end types in sync with a backend's JSON. Avoiding runtime surprises by adding types to untyped data. Speeding up work in a strict TypeScript project without writing every interface by hand.

Frequently Asked Questions