TypeScript Interface Generator — JSON to TypeScript [2026]
Instantly convert JSON to TypeScript interface definitions. Supports nested objects, arrays, and optional fields. Free json to typescript interface tool — no signup needed.
What is TypeScript Interface Generator?
How to Use TypeScript Interface Generator
1. Paste your JSON object into the left input panel (or click "Load Sample" to use an example). 2. Optionally change the interface name in the name field (default: MyInterface). 3. The TypeScript interface is generated instantly in the right panel. 4. Click "Copy" to copy the interface to your clipboard and paste it into your TypeScript project.
How TypeScript Interface Generator Works
Common Use Cases
- Generating TypeScript interfaces from REST API responses
- Typing JSON configuration files in TypeScript projects
- Converting mock data objects into reusable TypeScript types
- Quickly onboarding a JavaScript project to TypeScript with proper types
- Learning TypeScript by seeing how JSON shapes map to interface definitions
Frequently Asked Questions
What is the difference between a TypeScript interface and a type?▼
Both interface and type can describe object shapes, but interfaces are more extensible (they can be merged via declaration merging) and are idiomatic for defining object shapes. Types are more flexible for unions, intersections, and aliases for primitive types. For simple object shapes from JSON, either works — this tool generates interfaces by convention.
Does this tool handle nested objects?▼
Yes. The tool recursively processes nested objects and generates nested TypeScript interfaces or inline object types. Each level of nesting is properly indented so the output is immediately readable.
How are arrays handled?▼
Arrays are typed based on their first element. For example, an array of strings becomes string[], an array of numbers becomes number[], and an array of objects becomes an inline object type followed by []. Empty arrays default to unknown[].
What happens with null values in JSON?▼
Null values in JSON are typed as null in the generated interface. In practice you may want to change these to string | null or number | null depending on the actual API contract, since JSON null only tells us the current value is absent, not the full type.
Can I use this for large API responses?▼
Yes. The tool processes the full JSON you paste in, no matter how large. All computation runs locally in your browser, so there is no server-side size limit. For very large payloads, generation may take a moment, but your data never leaves your machine.
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