What is JSON to TypeScript Conversion?
JSON to TypeScript conversion analyzes JSON data and generates matching TypeScript interface definitions. When you're consuming APIs or working with configuration files, you need types that match your data structures. This tool automates that tedious process.
Instead of manually typing out interfaces, paste your JSON and get instant type definitions. The tool handles nested objects, arrays, and various data types, producing clean TypeScript code ready to use in your project.
Why TypeScript Interfaces Matter
Working with untyped JSON in TypeScript defeats the language's purpose. Using 'any' everywhere provides no safety. With proper interfaces, your editor provides autocomplete for property names, catches typos, and documents the expected structure.
Type errors surface during development rather than production. When an API changes, TypeScript tells you exactly where your code needs updates. This safety becomes increasingly valuable as codebases grow.
How Type Inference Works
The converter examines each value in your JSON to determine its type. Strings become 'string', numbers become 'number', booleans become 'boolean', and null becomes 'null'. Objects generate nested interfaces.
Arrays are typed based on their contents. Homogeneous arrays (all same type) get clean types like 'string[]'. Mixed arrays produce union types like '(string | number)[]'. Empty arrays become 'any[]' since there's nothing to infer from.
Handling Nested Structures
Nested objects get their own interface definitions. A user object with an address object produces both 'User' and 'Address' interfaces. The property types reference these generated interfaces appropriately.
This produces cleaner, more reusable code than inline object types. You can import and reuse these interfaces throughout your application.
After Generation
The generated interfaces are a starting point:
- Rename 'RootObject' to something meaningful
- Add optional markers (?) for fields that might be absent
- Consider union types for fields that can have multiple forms
- Add JSDoc comments for documentation
- Move interfaces to appropriate files in your project
Privacy Note
All conversion happens in your browser. Your JSON data never leaves your device. This makes it safe to convert responses from production APIs or configuration files containing sensitive information.
The tool is perfect for working with private API data without security concerns.
Frequently Asked Questions
What is JSON to TypeScript conversion?
This tool analyzes your JSON data structure and generates corresponding TypeScript interface definitions. It infers types from values: strings become 'string', numbers become 'number', and nested objects become nested interfaces.
Why use TypeScript interfaces for JSON?
Interfaces provide type safety when working with JSON data in TypeScript. Instead of treating API responses as 'any', you get autocomplete, type checking, and documentation. Bugs get caught at compile time rather than runtime.
How does the tool handle arrays?
Arrays are typed based on their contents. An array of strings becomes 'string[]', numbers become 'number[]'. Mixed types become union types like '(string | number)[]'. Empty arrays become 'any[]' since the type can't be inferred.
What about null and optional values?
Null values are typed as 'null'. The tool can't know if a field is optional from a single JSON example - you may need to add '?' to properties that aren't always present in your actual data.
Can I customize the generated interface name?
The tool generates a root interface named 'RootObject'. You should rename it to something meaningful for your project like 'User', 'ApiResponse', or 'Product' after copying.