JAVA

JSON to Java Converter

Generate Java POJO classes from JSON data. Paste your JSON and pick Lombok, records, Jackson or Gson — the Java output updates as you type.

Class

Package

Lombok Records (Java 16+) Jackson Gson

JSON Input

Java Output

package com.example.model;

import java.util.List;
import lombok.Data;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

@JsonIgnoreProperties(ignoreUnknown = true)
@Data
public class Root {
    private Integer id;

    private String username;

    private String email;

    private Boolean isActive;

    private List<String> roles;

    private Profile profile;

    @JsonIgnoreProperties(ignoreUnknown = true)
    @Data
    public static class Profile {
        private String firstName;

        private String lastName;

        private Integer age;
    }
}

How the JSON to Java converter works

Each JSON object becomes a Java class and nested objects become static nested classes. Arrays become List<T>, with the item type merged across every element. Whole numbers map to Integer (or Long when they exceed the int range), decimals to Double, and null or mixed values to Object. Keys that are not valid Java identifiers are renamed to camelCase and annotated with @JsonProperty or @SerializedName so serialization still matches your JSON.

Frequently Asked Questions

What is JSON to Java Converter?

It is a free browser tool that turns JSON data into Java POJO classes. Paste JSON and it generates a class for every object, with nested classes, List types, and optional Lombok, record, Jackson and Gson support.

How are JSON types mapped to Java types?

Strings become String, true/false become Boolean, whole numbers become Integer (or Long when they exceed the int range), decimals become Double, arrays become List<T>, and nested objects become their own classes. null and mixed-type values become Object.

What does the Lombok option do?

It adds the Lombok @Data annotation instead of writing getters and setters by hand, which keeps classes short. Without Lombok the tool generates standard getter and setter methods.

When should I use Java records?

Records (Java 16 and later) are compact, immutable data carriers — ideal for DTOs and API responses. Enable Records to generate record types; Lombok is switched off automatically because records already provide accessors, equals, hashCode and toString.

What do the Jackson and Gson options add?

Jackson adds @JsonIgnoreProperties(ignoreUnknown = true) so extra JSON fields do not break parsing, and @JsonProperty on renamed fields. Gson adds @SerializedName on renamed fields. Keys like "first-name" or "user_id" are converted to camelCase Java names and annotated so they still map to the original JSON key.

How are arrays of objects handled?

All objects in an array are merged into one class, so fields that appear in only some items are still included. The class name is the singular form of the array key — for example "addresses" becomes Address.

Is my JSON sent to a server?

No. The conversion runs entirely in your browser, so your JSON — including any sensitive values — never leaves your device.

Is JSON to Java Converter free to use?

Yes. All Neemtools utilities are free to use with no signup required.

Is my data uploaded when I use JSON to Java Converter?

For most tools, processing happens in your browser and your input is not stored on our servers. A few tools may fetch live URLs when that feature requires external data — each tool page explains what applies.

Do I need an account to use JSON to Java Converter?

No account is required. Open the tool and start using it immediately.