Nested Interfaces
Objects inside objects each get their own named interface, so the output reads like code you would write.
JSON to TypeScript Converter
Paste any JSON and get clean TypeScript interfaces or types right away. Nested objects become their own interfaces and arrays are merged into one shape. Free, no signup, runs in your browser.
Guide
How to convert JSON to TypeScript
1
Paste Your JSON
Drop in an API response or any JSON object on the left. The types build as you type.
2
Set Your Options
Name the root type, pick interface or type, and toggle export and readonly to fit your code.
3
Copy The Types
Copy the generated TypeScript or download it as a .ts file and drop it into your project.
Stop Hand Typing Types From API Responses
When you wire up a new API, the tedious part is writing the TypeScript to match. You copy a sample response, then type out every field, guess at the right types, and chase down the nested objects. Miss one and the compiler complains, or worse, it does not and you get a runtime surprise. A converter does that grunt work in a second.
Paste a JSON object and this tool walks the whole structure and writes the matching interfaces. Nested objects become their own named interfaces instead of one giant inline blob, so the result is easy to read and reuse. Arrays of objects are merged into a single shape, and if a key only appears in some items it is marked optional with a question mark. Mixed types turn into a union, and identical shapes are reused instead of duplicated.
You control the output too. Name the root type, switch between interface and type, and toggle the export keyword or readonly fields to match your house style. It all runs in your browser, so even private API payloads stay on your machine.
Benefits
Why Use Our JSON to TypeScript Converter?
Smart Arrays
Arrays of objects are merged into a single shape, and keys missing from some items are marked optional.
Unions And Optionals
Mixed value types become a union, and nullable or missing fields are handled so the types actually compile.
Interface Or Type
Choose interface or type alias, add the export keyword, and make fields readonly with one click.
Live Output
Types regenerate as you type or change a setting, with copy and a .ts download ready.
In Your Browser
Your JSON is parsed on your device. Nothing is uploaded, which keeps private payloads private.
Explore More
Similar Tools
More Developer tools you might find useful.
FAQ
Frequently Asked Questions
Common questions about converting JSON to TypeScript.
How does it convert JSON to TypeScript?
It parses your JSON, then walks the structure and writes a matching interface for every object it finds. Field types come from the values, nested objects become their own interfaces, and arrays of objects are merged into one shape. You get the result instantly, ready to copy or download as a .ts file.
How are arrays handled?
Arrays of objects are merged into a single interface that covers every key seen across the items. If a key appears in some items but not all, it is marked optional with a question mark. Arrays of primitives become a typed array, like string[], and mixed arrays become a union of the types found.
Can I choose interface or type?
Yes. A toggle switches the whole output between TypeScript interfaces and type aliases. You can also add the export keyword so the types are importable, make every field readonly, and treat null values as optional fields, all with simple switches.
What happens with null values?
By default a null value is typed as null, since the real type cannot be known from one sample. If you turn on the null means optional setting, those fields are marked optional and the null is dropped from the type, which is often closer to what an API actually returns.
Is my JSON uploaded anywhere?
No. The JSON is parsed and converted entirely in your browser, so nothing is uploaded, logged, or stored on a server. That makes it safe to paste private API responses, and there is no signup or limit on how much you convert.
Is the JSON to TypeScript converter free?
Yes, it is completely free with no limits and no signup. Convert as much JSON to TypeScript as you need.