JSON to TypeScript Interface Generator

Transform JSON objects and API responses into clean, fully-typed TypeScript interfaces, types, and definitions with zero server uploads.

At a glance

JSON to TypeScript Interface Generator is a free web tool that converts JSON to TypeScript interfaces and types online. It generates precise TypeScript types for primitives, arrays, union types, and complex nested objects. Nothing is uploaded and no sign-up is needed — everything runs on your device.

Universal Switcher:
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100% Client-Side In-Browser TypeScript Generation

API payloads, JSON structures, and sensitive database exports are analyzed strictly in your browser memory. Zero code or data is sent over the network.

Pure In-Browser
Sample Presets:
Valid JSON 0 chars
0 B
Root Type
-
Interfaces
0
Properties
0
Output Size
0 B

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Why Use This JSON to TypeScript Interface Generator?

Intelligent Type Inference: Generates precise TypeScript types for primitives, arrays, union types, and complex nested objects.
Ragged Array Schema Unioning: Inspects every element in array payloads to infer complete schemas, marking missing fields as optional (?).
Configurable Output Declarations: Easily toggle between interface declarations and type aliases with optional export and readonly modifiers.
Invalid Identifier Escaping: Automatically formats property keys with special characters, spaces, or hyphens into quoted keys.
One-Click Copy & .ts Export: Instantly copy generated TypeScript code to clipboard or download as a .ts definition file.
100% Client-Side Privacy: All parsing and TypeScript code synthesis execute locally in your web browser with zero server uploads.

How to Use JSON to TypeScript Interface Generator

1

Paste JSON or Upload File

Paste your JSON data or drop a .json file into the input editor.

2

Configure Root Name & Type Style

Set your root interface name, choose between interface or type alias, and toggle optional/readonly modifiers.

3

Copy or Download TypeScript

Inspect the generated TypeScript code, copy it to your clipboard, or download the .ts definition file.

Worked example: JSON to TypeScript Interfaces

Infers primitive TypeScript types (string, number, boolean), constructs nested interfaces for sub-objects, and resolves nullable properties with union types.

Sample JSON Payload Source 
{
  "id": "usr_992",
  "name": "Sarah Connor",
  "isActive": true,
  "score": 98.5,
  "metadata": {
    "loginCount": 12,
    "lastIp": null
  }
}
Generated TypeScript Interface Processed 
export interface UserResponse {
  id: string;
  name: string;
  isActive: boolean;
  score: number;
  metadata: UserMetadata;
}

export interface UserMetadata {
  loginCount: number;
  lastIp: null | string;
}

Technical Specifications & Engine Details

Technical specifications and engine details for JSON to TypeScript Interface Generator
Specification Details
Supported Formats JSON, TEXT → TYPESCRIPT, TS
Execution Mode 100% Client-Side In-Browser (client)
Browser Requirements Requires modern web browser with ECMAScript 6+ and standard DOM Web APIs.
Performance Constraints Client browser memory limit (typically 1–2 GB RAM); processing speed depends on local device CPU.
Maintained by Pragyan Pahadi

100% Client-Side Privacy Guarantee

All JSON parsing and TypeScript generation run 100% locally in your browser memory. No data is transmitted to external servers.

Frequently Asked Questions

Is my JSON API data uploaded to an external server?
No. All schema inference and TypeScript generation run 100% locally in your web browser. Your private API structures and database records never leave your computer.
How does the generator handle optional fields in arrays?
When you input an array of objects, the engine checks every record. If a property is missing in any object, it automatically adds the optional operator (?) to that property.
Can I generate type aliases instead of interfaces?
Yes. You can switch between TypeScript interface declarations and type alias definitions with a single toggle.
Are nested objects converted into separate interfaces?
Yes. Nested objects are recursively extracted and assigned clean PascalCase interface names (e.g., Address, Company), keeping your type definitions clean and modular.

Methodology

Rankings and recommendations here are never paid for.

Last updated .

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