JSON to TypeScript Interface

Convert JSON into TypeScript interfaces.

JSON Input:

TypeScript Interface Output:

About JSON to TypeScript Interface

The JSON to TypeScript Interface Generator is an essential tool for frontend and full-stack developers that converts JSON data payloads into clean, strongly-typed TypeScript interfaces. It automatically parses scalar values, infers union types, resolves arrays of objects, decomposes nested structures into individual modular interfaces, and marks nullable fields as optional. Built to streamline TypeScript development across React, Next.js, Vue, Node.js, and API integrations.

Key features

Recursive Interface Extraction: Breaks down complex nested JSON hierarchies into discrete, reusable TypeScript interfaces
Precise Type Inference: Accurately differentiates string, number, boolean, Array<T>, and Record<string, T> types
Safe Optional & Union Detection: Detects null and missing attributes across array elements to generate optional properties (key?: type)
Fast Client-Side Execution: Generates ready-to-use TypeScript definitions instantly in browser memory with zero network latency

How to use

Paste JSON Object: Paste your JSON sample or API response into the source code editor.
Inspect Generated Interfaces: Review the generated TypeScript interfaces and inferred property types in real time.
Copy TypeScript Definitions: Click "Copy" to paste the interfaces directly into your .ts or .d.ts type definition files.

FAQ

How are heterogeneous arrays typed?

When an array contains multiple element types (e.g., numbers and strings), the generator infers a union type like Array<string | number>.

Are nested JSON objects represented as separate interfaces?

Yes. Instead of unreadable inline type literals, each nested object is extracted into its own named, PascalCase TypeScript interface.

Does it support optional properties?

Yes. Properties that evaluate to null or are missing across items in an array are marked with the optional modifier (?).

Is any of my JSON data transmitted across the web?

No. All JSON parsing and TypeScript type generation run 100% client-side in your browser.

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About JSON to TypeScript Interface

Key features

Recursive Interface Extraction: Breaks down complex nested JSON hierarchies into discrete, reusable TypeScript interfaces

Precise Type Inference: Accurately differentiates string, number, boolean, Array<T>, and Record<string, T> types

Safe Optional & Union Detection: Detects null and missing attributes across array elements to generate optional properties (key?: type)

Fast Client-Side Execution: Generates ready-to-use TypeScript definitions instantly in browser memory with zero network latency