JSON to TypeScript Interface Converter
Paste your JSON and instantly get clean TypeScript interfaces. Handles nested objects, arrays, optional fields, and union types. 100% browser-based — your data stays on your device.
How JSON to TypeScript Interface Converter Works
Convert JSON to TypeScript interfaces instantly. Paste JSON, get typed interfaces with nested objects, arrays, and union types. Select your input and output formats, enter your value, and the tool converts it instantly in your browser with no server calls.
How to Convert JSON to TypeScript Interfaces
Paste any valid JSON into the left panel and click "Convert to TypeScript." The tool analyzes the structure of your JSON — including nested objects, arrays, and primitive types — and generates clean TypeScript interfaces. Each nested object gets its own named interface. Arrays are typed based on their contents, and mixed-type arrays produce union types. Everything runs in your browser with zero data sent to any server.
Why Use TypeScript Interfaces for JSON Data
TypeScript interfaces provide type safety when working with JSON data from APIs, configuration files, or databases. Instead of using any types, proper interfaces catch errors at compile time, enable autocomplete in your IDE, and make your code self-documenting. This converter saves time by automatically generating interfaces from sample JSON responses — paste your API response and get production-ready types instantly.
Features of This JSON to TypeScript Converter
This tool handles complex JSON structures including deeply nested objects, arrays of objects (typed with shared interfaces), mixed-type arrays (union types), null values (typed as null in unions), and empty arrays (typed as any[]). Options include: export keyword toggle, readonly properties, optional fields with ?, and semicolon preference. The generated interfaces follow TypeScript best practices with PascalCase naming conventions.
JSON to TypeScript vs JSON to Type
TypeScript offers both interface and type declarations. Interfaces are preferred for object shapes because they can be extended, merged, and are more readable in error messages. Types are better for unions, intersections, and mapped types. This tool generates interfaces by default, which is the recommended approach for most API response typing and data modeling use cases.
Frequently Asked Questions
How does JSON to TypeScript conversion work?
The tool parses your JSON, analyzes the structure of each property (strings, numbers, booleans, nested objects, arrays), and generates TypeScript interfaces that match the shape of your data. Nested objects get their own named interfaces.
Does this handle nested JSON objects?
Yes. Every nested object automatically gets its own TypeScript interface with a PascalCase name derived from the property key. Deeply nested structures are fully supported.
What happens with arrays in JSON?
Arrays are typed based on their contents. An array of strings becomes string[], an array of objects generates a typed interface, and mixed-type arrays produce union types like (string | number)[].
Can I customize the generated interfaces?
Yes. You can set the root interface name, toggle export keywords, make all properties readonly, make all properties optional with ?, and choose whether to include semicolons.
Is my JSON data sent to a server?
No. Everything runs locally in your browser using JavaScript. Your JSON is never uploaded or transmitted. Safe for API keys, credentials, and sensitive data structures.
What about null values in JSON?
Null values are typed as any | null since the actual type cannot be inferred from null alone. You can manually refine these types in your code.
Does this support JSON with special characters in keys?
Yes. Keys with special characters (spaces, hyphens, dots) are automatically wrapped in quotes in the generated interface, e.g. 'my-key': string.