JSON to Java Converter Online — Generate POJO Classes

Writing model classes by hand from a 200-field API payload wastes hours and is bug-prone — a single typo in a field name silently nulls out a value at runtime. OpenFormatter's converter walks the JSON tree once, generates idiomatic Java, and runs entirely in your browser so internal API responses never leave your machine.

How to generate Java POJOs from JSON — 4 steps

1. Paste a real JSON response. Use a representative sample — the type inference quality depends on it. Booleans must be true/false (not 0/1), numbers must be unquoted.
2. Click Convert. The tool emits a Root class plus one separate class per nested object, with private fields and public getters/setters.
3. Copy and paste into your IDE. Each class is independent — split them into separate .java files in your com.example.model package.
4. Deserialize. Root r = new ObjectMapper().readValue(json, Root.class); — that is all Jackson needs once the POJO has a no-arg constructor and setters.

JSON to Java type mapping

{
  "id": 42,
  "name": "Ada Lovelace",
  "active": true,
  "score": 98.5,
  "address": { "city": "London" },
  "tags": ["admin", "engineer"]
}

import java.util.List;

public class Root {
    private int id;
    private String name;
    private boolean active;
    private double score;
    private Address address;
    private List<String> tags;

    public int getId() { return id; }
    public void setId(int val) { this.id = val; }
    public String getName() { return name; }
    public void setName(String val) { this.name = val; }
    public boolean isActive() { return active; }
    public void setActive(boolean val) { this.active = val; }
    // ... etc
}

public class Address {
    private String city;
    public String getCity() { return city; }
    public void setCity(String val) { this.city = val; }
}

Common use cases

• check_circleGenerating Spring Boot @RestController request and response DTOs from a frontend JSON payload
• check_circleBuilding Jackson-deserializable models for a third-party REST API (Stripe, Slack, GitHub)
• check_circleProducing Android Retrofit response bodies from a JSON spec
• check_circleGenerating Lombok @Data classes after copying — strip getters/setters and add @Data
• check_circleModelling Kafka or RabbitMQ JSON event payloads as typed POJOs
• check_circleBuilding Micronaut or Quarkus serverless function request/response classes
• check_circleGenerating GraphQL response shapes when a tool like Apollo codegen is overkill
• check_circleModelling configuration files (application.json) into typed @ConfigurationProperties

Why client-side generation matters

The JSON you paste often contains real customer data, OAuth tokens, signed URLs, or internal field names you do not want indexed by a third-party converter. OpenFormatter generates the Java entirely in JavaScript on your device — open the Network tab in DevTools and you will see zero requests when you click Convert. Safe for enterprise use, safe behind a corporate proxy, safe when the API contract is itself confidential.