JSON to TypeScript
Generate TypeScript interfaces from JSON with optional readonly modifiers and JSDoc comments.
JSON to TypeScript Generator
Generate TypeScript interfaces from JSON with optional readonly modifiers and JSDoc comments.
Prepend readonly to every property
Add /** */ comments above each property
Terminate property declarations with ;
Paste JSON to generate TypeScript interfaces.
What is JSON to TypeScript?
A JSON to TypeScript converter generates TypeScript interfaces, types, and type definitions from JSON data. Paste your JSON and get production-ready TypeScript code with proper type annotations, optional properties, readonly modifiers, and JSDoc comments. This tool is essential for TypeScript developers working with APIs, configuration files, or any JSON data — it automates the tedious work of writing type definitions by hand, ensures type safety, and saves time. The converter handles nested objects, arrays, unions, and complex structures, generating clean, idiomatic TypeScript that compiles without errors. Use it to generate types for API responses, database models, configuration schemas, or any structured data.
How to use JSON to TypeScript
- Paste your JSON data into the left panel — the tool analyzes the structure automatically.
- Choose generation options: interface name, readonly modifiers, JSDoc comments, or semicolons.
- The TypeScript code appears instantly on the right with statistics on interfaces and properties.
- Click Copy to grab the generated TypeScript, or customize the interface name for your use case.
- For arrays, the tool generates separate item interfaces to keep the code clean and maintainable.
Examples
User object → TypeScript interface
Input
{ "id": 1, "name": "Alice", "email": "alice@example.com", "active": true, "roles": ["admin", "user"] }
Output
export interface GeneratedData { /** Property 'id' from input */ id: number; /** Property 'name' from input */ name: string; /** Property 'email' from input */ email: string; /** Property 'active' from input */ active: boolean; /** Property 'roles' from input */ roles: string[]; }
Nested structure → Multiple interfaces
Input
{ "user": { "name": "Bob", "address": { "street": "123 Main St", "city": "San Francisco" } } }
Output
export interface GeneratedData { /** Property 'user' from input */ user: GeneratedDataUser; } export interface GeneratedDataUser { /** Property 'name' from input */ name: string; /** Property 'address' from input */ address: GeneratedDataUserAddress; } export interface GeneratedDataUserAddress { /** Property 'street' from input */ street: string; /** Property 'city' from input */ city: string; }
Common mistakes
- Assuming generated types replace validation — TypeScript types at compile time don't validate data at runtime (they're erased during compilation). For runtime validation, use a JSON Schema validator or Zod/io-ts schemas alongside your types.
- Treating all properties as required — the tool generates required properties by default, but real-world data often has optional fields. Add ? to properties that may be missing: email?: string instead of email: string.
- Not customizing interface names for context — generated names like 'GeneratedData' are placeholders. Rename them to match your domain: UserProfile, ApiResponse, ConfigFile — meaningful names improve code readability.
Why use this tool
- Instant type generation — paste JSON, get TypeScript with no manual typing or guessing at types. Handles nested structures and arrays automatically.
- Production-ready code — generates clean, idiomatic TypeScript with proper formatting, optional JSDoc comments, and statistics on the generated types.
- Customizable output — control interface naming, readonly modifiers, semicolons, and JSDoc comments to tailor the generated code to your project's style guide.