How are nested JSON objects handled?

Nested objects are automatically generated as independent Java inner or outer classes, linked by type references.

Is my data uploaded to a server?

No. All processing happens locally in your browser using pure frontend technology.

How are null value fields handled?

Null fields use wrapper types (Integer instead of int) by default. Optional wrapping is available.

Free JSON to Java Class Generator

What is JSON to Java Class Generator?

The JSON to Java Class Generator is an online tool designed for Java developers that automatically converts JSON data into Java POJO class code. Paste your JSON data, and the tool instantly infers field types, generates nested classes, handles List/Map types, and outputs ready-to-use Java code—dramatically reducing manual POJO writing.

Core Features

Smart Type Inference: Automatically identifies String, Integer, Long, Double, Boolean, List, Map Java types
Nested Class Generation: Nested JSON objects are automatically generated as independent Java inner or outer classes
Lombok Support: Optional @Data, @Builder annotations to reduce boilerplate code
Getter/Setter: Optional standard getter/setter method generation
Custom Class Names: Customize root class name; nested classes are auto-named

How to Use

Step 1: Paste or type JSON data in the input area, or click example buttons to load samples.

Step 2: Adjust options—Lombok, Getter/Setter, class name.

Step 3: The tool generates Java code in real-time in the result area.

Step 4: Click "Copy Code" or "Download .java" to save. Shortcuts: Ctrl+Enter to regenerate, Ctrl+Shift+C to copy.

Use Cases

Case 1: Spring Boot Development

Spring Boot developers receive JSON examples from API docs and quickly generate POJO entity classes for Controller and Service layers.

Case 2: JSON Deserialization

Java developers integrating REST APIs convert JSON responses to POJO classes for automatic deserialization with Jackson/Gson.

Case 3: Data Model Design

Backend developers generate Java data models from frontend-provided JSON structures, ensuring frontend-backend consistency.

Extended Knowledge

POJO (Plain Old Java Object) is Java's simplest data carrier class with only fields and getters/setters. Lombok generates getter/setter/toString/equals/hashCode at compile time via annotations, reducing boilerplate. Jackson and Gson are Java's most popular JSON serialization libraries, using reflection for JSON-POJO conversion. Java 8's Optional provides safer null handling.

❓ FAQ

What Java types are supported?

String, Integer, Long, Double, Boolean, List, Map, LocalDateTime, and nested POJO classes.

How are nested objects handled?

Nested objects generate independent Java inner classes linked by type references.

Is my data uploaded?

No. All processing happens locally in your browser.

Does it generate Lombok annotations?

Optional. Enable to auto-add @Data, @Builder annotations.

How are null fields handled?

Null fields use wrapper types (Integer vs int). Optional wrapping is available.

Can I use the generated code directly?

Yes. Copy into your Java project. Add Lombok dependency if enabled.

☕ JSON to Java Class Generator

📥 JSON Input

📤 Java Code