JSON to Java Class Generator
Paste any JSON object or API response and instantly generate Java POJO classes with nested types, getters, setters, and constructor support — no sign-up needed.
Why Generate Java Classes from JSON?
When consuming REST APIs in a Java or Spring Boot project, you need accurate POJO definitions to deserialise responses with Jackson or Gson, enable IDE autocomplete, and catch field-name mismatches at compile time rather than at runtime. Writing these classes by hand from a large API response is slow and error-prone — a single missing field or incorrect type can cause NullPointerException or silent data-loss bugs in production.
This JSON to Java class generator automates the entire process. Paste the API response, copy the generated POJOs, and drop them straight into your codebase. It handles deeply nested objects, lists of objects, all primitive types, and generates standard getter and setter methods automatically — giving you production-ready Java classes in seconds instead of minutes.
Java POJO Generation — How It Works
The converter parses your JSON using the browser's native JSON.parse API, then walks the resulting object tree recursively. For each object it encounters, it creates a named Java class whose field types are inferred from the value types: String, int, double, boolean, List<T>, or child class references. Class names are derived from the JSON key using PascalCase, keeping the output readable and consistent with Java naming conventions. Everything runs locally in your browser — no data is ever sent to a server.
Frequently Asked Questions
What does a JSON to Java class generator do?
A JSON to Java class generator analyses a JSON object and produces Java POJO (Plain Old Java Object) class definitions that match its structure. Every key becomes a typed field, nested objects become inner classes or separate class files, and arrays are typed as List<T>. This eliminates the need to write boilerplate Java code by hand when consuming REST API responses in a Java or Spring Boot project.
What Java types are used for JSON primitive values?
The generator maps JSON primitives to standard Java types: JSON strings become String, JSON numbers without a decimal become int or long depending on magnitude, JSON numbers with a decimal become double, JSON booleans become boolean, and JSON null values result in the field type being annotated as nullable or declared with the wrapper type (e.g., Integer instead of int). This produces idiomatic, type-safe Java classes that compile without modification.
How are nested JSON objects handled in the generated Java classes?
Each nested JSON object generates its own separate Java class. The parent class holds a reference field of that child class type. For example, a JSON user object containing an address object produces a User class with an Address field of type Address, plus a standalone Address class with its own fields, getters, and setters. This mirrors standard Java object-oriented design and is compatible with Jackson, Gson, and other JSON serialisation libraries.
Are the generated Java classes compatible with Jackson and Spring Boot?
Yes. The generated POJOs follow standard Java Bean conventions with private fields and public getter/setter pairs, which makes them directly compatible with Jackson ObjectMapper used by default in Spring Boot. You can annotate the classes with @JsonProperty if your JSON keys use snake_case or other naming conventions that differ from Java camelCase. No additional configuration is needed for basic serialisation and deserialisation.
Do I need to install anything to use this JSON to Java tool?
No installation is required. The tool runs entirely in your browser — paste your JSON, click convert, and copy the generated Java classes. Your data never leaves your device, making it safe to use with sensitive API responses or internal configuration objects. It works on all modern browsers including Chrome, Firefox, Safari, and Edge, and requires no account or sign-up.