JSON to Java

Processed Client Side

Generate Java POJOs from a JSON sample — getters and setters, Lombok, or records, with optional Jackson annotations.

JSON · 14 lines

14 lines · 216 chars

{
  "id": 42,
  "user_name": "Ada",
  "active": true,
  "score": 9.5,
  "tags": ["admin", "engineer"],
  "profile": {
    "age": 36,
    "city": "London"
  },
  "posts": [
    { "title": "Hello", "views": 120 }
  ]
}

Length: 216Lines: 14Size: 216 BytesCursor: 1:1

Java

import com.fasterxml.jackson.annotation.JsonProperty;
import java.util.List;

public class Root {
    private int id;
    @JsonProperty("user_name")
    private String userName;
    private boolean active;
    private double score;
    private List<String> tags;
    private Profile profile;
    private List<Post> posts;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public boolean isActive() {
        return active;
    }

    public void setActive(boolean active) {
        this.active = active;
    }

    public double getScore() {
        return score;
    }

    public void setScore(double score) {
        this.score = score;
    }

    public List<String> getTags() {
        return tags;
    }

    public void setTags(List<String> tags) {
        this.tags = tags;
    }

    public Profile getProfile() {
        return profile;
    }

    public void setProfile(Profile profile) {
        this.profile = profile;
    }

    public List<Post> getPosts() {
        return posts;
    }

    public void setPosts(List<Post> posts) {
        this.posts = posts;
    }

    public static class Profile {
        private int age;
        private String city;

        public int getAge() {
            return age;
        }

        public void setAge(int age) {
            this.age = age;
        }

        public String getCity() {
            return city;
        }

        public void setCity(String city) {
            this.city = city;
        }
    }

    public static class Post {
        private String title;
        private int views;

        public String getTitle() {
            return title;
        }

        public void setTitle(String title) {
            this.title = title;
        }

        public int getViews() {
            return views;
        }

        public void setViews(int views) {
            this.views = views;
        }
    }
}

import com.fasterxml.jackson.annotation.JsonProperty;
import java.util.List;

public class Root {
    private int id;
    @JsonProperty("user_name")
    private String userName;
    private boolean active;
    private double score;
    private List<String> tags;
    private Profile profile;
    private List<Post> posts;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public boolean isActive() {
        return active;
    }

    public void setActive(boolean active) {
        this.active = active;
    }

    public double getScore() {
        return score;
    }

    public void setScore(double score) {
        this.score = score;
    }

    public List<String> getTags() {
        return tags;
    }

    public void setTags(List<String> tags) {
        this.tags = tags;
    }

    public Profile getProfile() {
        return profile;
    }

    public void setProfile(Profile profile) {
        this.profile = profile;
    }

    public List<Post> getPosts() {
        return posts;
    }

    public void setPosts(List<Post> posts) {
        this.posts = posts;
    }

    public static class Profile {
        private int age;
        private String city;

        public int getAge() {
            return age;
        }

        public void setAge(int age) {
            this.age = age;
        }

        public String getCity() {
            return city;
        }

        public void setCity(String city) {
            this.city = city;
        }
    }

    public static class Post {
        private String title;
        private int views;

        public String getTitle() {
            return title;
        }

        public void setTitle(String title) {
            this.title = title;
        }

        public int getViews() {
            return views;
        }

        public void setViews(int views) {
            this.views = views;
        }
    }
}

javaLength: 2105Lines: 112Size: 2105 BytesCursor: 1:1

Class namePackage

Jackson

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About JSON to Java

This tool runs entirely in your browser. Whatever you paste is processed on your own device and is never uploaded, logged, or sent to any server.

The JSON to Java converter turns a sample JSON payload into Java classes you can deserialize straight into with Jackson or Gson. Nested objects become their own types, emitted as static nested classes so the entire model stays in a single .java file that compiles as-is. Arrays become List<T>, and numbers are mapped to int, long, or double from the values actually present. Keys become camelCase fields with @JsonProperty where the Java name differs from the wire name, and you can generate plain POJOs with getters, Lombok-annotated classes, or Java records depending on what your codebase uses.

Key features

Three output styles: POJOs with getters and setters, Lombok-annotated classes, or Java records
Optional @JsonProperty annotations, emitted only where the Java field name differs from the JSON key
Optional package declaration, with imports added only when the model actually needs them
Nested objects emitted as static nested classes, so the whole model is one compilable file
Arrays of objects merged into a single type, with fields missing from some elements marked nullable
Boxed wrapper types (Integer, Boolean, Double) used for nullable fields and inside generics, primitives everywhere else
Numeric types inferred from the data — int, long past Int32 range, double for any fractional value
Java reserved words handled: a field that would be called class or public gets a trailing underscore instead of failing to compile
Syntax-highlighted Java output and one-click copy, generated entirely in your browser

How to use it

Paste a representative JSON response into the input pane.
Set the root class name, and a package such as com.example.model if you want the declaration emitted.
Pick the style — getters, Lombok, or record — and switch Jackson annotations on or off.
Press Convert and read the generated classes.
Copy the file into your project and deserialize with objectMapper.readValue(json, Root.class).

Tips & common mistakes

Paste the fullest sample you can find. Fields that are null in your only sample come out as Object, and empty arrays come out as List<Object>.
Nullable fields deliberately use Integer rather than int. A primitive cannot hold null, so an absent number would silently deserialize as 0 and hide a missing value.
Records are immutable and need Jackson 2.12 or later to deserialize without extra configuration. If you are on an older version, or a framework needs a no-args constructor, choose getters instead.
Lombok keeps the file short but requires the dependency and IDE plugin. Plain getters are the safer default for code that will be read more often than it is written.
Keep @JsonProperty on unless you have configured a global naming strategy. Without either, a snake_case key will not bind to a camelCase field and you will get a null with no error.
A key that appears with different types across samples becomes Object, because no single static type covers both. Fixing that on the API side is usually better than working around it in the model.
Working in C# instead? The JSON to C# converter runs the same analysis and emits classes or records with System.Text.Json or Newtonsoft attributes.

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Frequently asked questions

Paste a sample JSON response, set the root class name and optionally a package, pick the style, and press Convert. Copy the result into your project and deserialize with objectMapper.readValue(json, Root.class).

Plain POJOs with getters and setters, Lombok-annotated classes, and Java records. Records need Jackson 2.12 or later to deserialize without extra configuration.

So the whole model compiles as a single .java file. A non-static inner class needs an enclosing instance, which is not something a deserializer can provide.

Yes, unless you have configured a global naming strategy. Without either, a snake_case key will not bind to a camelCase field and the value arrives as null with no error.

Because they can be null. A primitive cannot hold null, so an absent number would silently deserialize as 0 — the boxed type keeps the missing value visible.

Every element is merged into one class, so elements with slightly different shapes still produce a single type. Fields present in only some elements are marked nullable.

It was null in every sample, or it held different types across samples. No single static type covers either case, so it falls back to Object.

Java reserved words get a trailing underscore, so a key named class becomes a field named class_ with a @JsonProperty annotation preserving the original name.

No. Everything runs in your browser, so pasting a real API response with production data is safe.

The JSON to C# converter runs the same analysis and emits classes or records with System.Text.Json or Newtonsoft attributes.

About JSON to Java

Key features

How to use it

Tips & common mistakes

Related tools

Frequently asked questions