01
Simple flat object
Paste {"id":1,"name":"Ada","active":true} to generate interface Root { id: number; name: string; active: boolean; }, with every type inferred straight from the sample values.
JSON to TypeScript Interface Generator
Developer ToolsConvert JSON to TypeScript interfaces online, including nested objects — free generator.
About
About the JSON to TypeScript Interface Generator
Reads a sample JSON object and generates a matching TypeScript interface, including a separate named interface for every nested object it finds.
Frontend and full-stack developers use it to quickly scaffold types for an API response without typing them out by hand, especially useful the first time they wire up a new endpoint. It's one of many free developer tools on Toolapt, and like every tool here, it's free to use with no sign-up and no limit on how many times you run it.
Examples
JSON to TypeScript Interface Generator examples
4 worked examples
02
Nested object gets its own interface
Paste {"user":{"id":1,"name":"Ada"}} and a separate interface User { id: number; name: string; } is generated, with the root interface referencing User as the property's type.
03
Array typed from its first element
Paste {"tags":["js","py"]} and the property comes out as tags: string[];, with the type taken from the array's first item.
04
Empty array
Paste {"items":[]} and since there's no element to infer a type from, the property comes out as items: any[];.
Related tools
FAQ
Frequently asked questions
Quick answers to common questions about the JSON to TypeScript Interface Generator.
What does the JSON to TypeScript interface generator do?
It infers a TypeScript interface — including any nested interfaces — from a sample JSON object.
Is the JSON to TypeScript generator free to use?
Yes. It's free, with no sign-up, no watermark and no limit on how many times you use it.
Is my JSON safe when I use this tool?
Yes. The interface is generated entirely on your own device — nothing you paste is sent to a server.
What happens if I paste a JSON array instead of an object?
The tool uses the first object in the array as the sample to infer the interface from.
How are nested objects handled?
Each nested object gets its own separate, named interface (named after its key), and the outer interface references that name as the property's type.
What type does an empty array get?
Since there's no element to infer a type from, an empty array is typed as any[].
Does the generated interface include optional (?) properties?
No. Every property from the sample object is generated as required; you may want to mark some as optional by hand if the real data can omit them.
Can I use this tool on my phone?
Yes. The page is fully responsive and works on mobile, tablet and desktop browsers alike.