JSON To Code Converter
Classes For Nine Languages

What A JSON To Code Converter Saves You

You get a JSON reply from an API. Now you need a class to hold it. Writing that class by hand is slow and dull. A typo in one field name breaks the whole thing.

This JSON to code converter does the dull part. Paste a sample, pick a language, and the classes appear. Copy them into your project and move on.

It reads the whole sample, not just the first item. So a field that is missing from some items becomes optional. A field that holds numbers and decimals becomes a double. A null makes a field nullable.

Nothing is uploaded. Your sample may hold real customer data. Because your browser does the work, none of it reaches this site.

Think about a typical day. A teammate adds a field to the API. Then your app fails in testing, because the class does not know the field. With generated models, you paste the new reply, copy the class, and the fix takes a minute. Also, you can compare the old and new code to see exactly what changed.

JSON To C# Class Online

Choose C# and you get plain classes with get; set; properties. Pick System.Text.Json or Newtonsoft.Json, and the tool adds the right attribute to every property. Keys like first-name become FirstName, and the attribute keeps the original name.

Dates in ISO format become DateTime. Optional fields become nullable types, so your code stays honest about what may be missing.

Also, the tool writes a default for required strings, so your code does not hit null by surprise. Then you can add your own logic around the class.

For more detail, see: RFC 8259, the JSON standard.

JSON To Java Class Online

Java gets private fields with getters and setters, the classic bean shape. Add Jackson, and each field carries a @JsonProperty annotation. Or choose Lombok, and the tool writes @Data instead of the long accessors.

Numbers use the boxed types, such as Integer and Double. That way a missing value can be null.

Records are another option in modern Java, but beans work everywhere. That is why this tool writes the bean shape. Then you can turn it into a record by hand if you like.

TypeScript, Kotlin, Go And More

TypeScript gets interfaces, or types if you prefer. An optional field gets a question mark. Kotlin gets data classes, with kotlinx.serialization if you want it.

Go gets structs with JSON tags, and optional fields get omitempty. Python gets dataclasses, Pydantic models or TypedDicts. PHP gets typed classes with promoted properties. Swift gets Codable structs, and Rust gets serde structs.

Optional Fields And Nulls

Real data is messy. One order has a coupon, and the next does not. The tool compares every item in a list. If a key is missing from any of them, the field is optional.

A key that holds null in the sample becomes nullable. You can turn the optional rule off if your API always sends every field.

Why does this matter? Because a parser that sees a missing key may throw an error, or may fill a default you did not expect. So nullable types make the intent clear. Then your code must handle the empty case.

Smart Types From Real Values

Whole numbers become int. Whole numbers too big for int become long. Anything with a fraction becomes a double. Text that looks like an ISO date becomes a date type where the language has one.

Safe Names

Keys can break a language. class and new are reserved words. first-name has a dash. The tool renames these safely, and keeps a link to the real key so the data still maps.

For example, a key named 123 becomes _123 in C#, because a name cannot start with a digit.