Should I use Java Records or Lombok for JSON conversion?

For DTOs (Data Transfer Objects) that simply carry data, use Java Records as they are immutable and standard. For JPA Entities, use Lombok as Hibernate requires mutable objects.

Is it safe to use online JSON to Java converters?

It is safe if the tool is 'Client-Side'. Toolshref's converter processes data locally in your browser using JavaScript, meaning your JSON is never uploaded to a server.

How to Convert JSON to Java POJO Instantly (The "No-Code" Way) -

Q: How do I fix UnrecognizedPropertyException in Jackson?

This occurs when JSON has fields missing in your Java class. You can fix it by adding @JsonIgnoreProperties(ignoreUnknown = true) to your class level, or by ensuring all JSON keys are mapped to class fields.

How to Convert JSON to Java POJO “No-Code” Way

You are building a Spring Boot application. You need to consume a third-party API—maybe it’s a massive response from Stripe, Salesforce, or a legacy internal system.

You copy the JSON response. It’s 500 lines long. It has nested arrays, three levels of objects, and fields named "customer_id_v2" that violate Java’s camelCase naming conventions.

Now you have two choices:

The Hard Way: Manually create 10 different Java classes, type out private fields for every property, add getters/setters, and debug UnrecognizedPropertyException errors when you miss a field.
The Smart Way: Generate the entire POJO structure instantly, complete with Jackson annotations and Lombok decorators.

In this guide, we will show you how to automate the most boring part of Java development: Mapping JSON to Java Objects.

Have a massive JSON file?

Don’t hand-code the classes. Generate Java 17 Records or Lombok POJOs instantly.

👉 Open JSON to Java Converter

The Pain of Manual Mapping (Why It Breaks)

Writing POJOs (Plain Old Java Objects) by hand isn’t just boring; it’s dangerous. Here are the three most common bugs that happen when you try to map JSON manually:

1. The `snake_case` Trap

APIs often return keys like "user_first_name". In Java, you want userFirstName. If you just define the field as private String userFirstName;, Jackson (the default JSON library in Spring Boot) will fail to map the data because the names don’t match.

You have to remember to add @JsonProperty("user_first_name") to every single field. Missing just one results in null values in your database.

2. The “Nested Object” Nightmare

JSON is hierarchical. A User object might contain an Address object, which contains a GeoLocation object.

{

"user": { "address": { "geo": { "lat": 10.0, "lng": 20.0 } } } }

To map this manually, you have to create three separate files (User.java, Address.java, Geo.java) and link them correctly. It takes 20 minutes to do what should take 10 seconds.

3. Type Mismatches

Is that "id": 12345678901 an Integer? No, it’s too big. It’s a Long. If you guess wrong, your app crashes with a MismatchedInputException at runtime.

The Solution: Automated Code Generation

The standard best practice in 2026 is to use a JSON to Java Converter. These tools parse the raw JSON payload and reverse-engineer the class structure for you.

However, not all converters are created equal. Most old tools only generate basic Java classes (getters/setters). Modern development requires modern patterns:

Lombok Support: Using @Data to remove boilerplate.
Java Records: Using the record keyword for immutable DTOs (Java 16+).
Builder Pattern: Using @Builder for cleaner object creation.

How to Generate Production-Ready Code

Here is the workflow used by senior engineers to handle new API integrations:

Step 1: Get the Response

Make a request to the API (using Postman or curl) and copy the full JSON response body.

Step 2: Convert to Java

Paste the JSON into a privacy-first tool like Toolshref’s Converter.
Select your target architecture:

For Spring Boot DTOs: Select “Java Record” (Fastest, Immutable).
For JPA Entities: Select “Lombok” (Mutable, Compatible with Hibernate).

Step 3: Verify Annotations

Ensure the tool has added the correct library annotations.
Check: Does it have @JsonProperty for Jackson? Does it have @SerializedName if you are using Gson?

Step 4: Copy & Paste

Copy the generated code directly into your IntelliJ/Eclipse project. The entire nested structure is created as inner static classes or can be split into separate files.

Why Use Toolshref Over IntelliJ Plugins?

IntelliJ has plugins for this, but they often bloat your IDE or require configuration for every new project. Using a browser-based converter is faster for quick lookups.

More importantly, Toolshref runs 100% Client-Side.

If you are working in Fintech or Healthcare, pasting customer JSON into a web converter is a security risk if that converter uploads data to a server. Our tool parses the JSON locally in your browser using JavaScript. No data ever leaves your machine.

Frequently Asked Questions

Should I use Java Records or Lombok?

For DTOs (Data Transfer Objects) that just carry data from an API to your frontend, use Java Records. They are immutable and built into the JDK. For Database Entities (Hibernate/JPA), use Lombok because JPA requires mutable objects with getters/setters.

What is the `UnrecognizedPropertyException` error?

This error happens when the JSON contains a field that does not exist in your Java class. You can fix it by adding the missing field OR by adding @JsonIgnoreProperties(ignoreUnknown = true) to the top of your class.

How do I handle Date fields?

JSON doesn’t have a date type, so dates appear as Strings (e.g., “2023-10-01”). A good converter will map these to `String` by default. You should manually change them to `LocalDate` or `ZonedDateTime` and add @JsonFormat to specify the pattern.

Conclusion

Stop wasting your coding time on boilerplate. Hand-writing Java mapping classes is a relic of the past.

Next time you have a massive JSON payload, use a generator to do the heavy lifting. You will get cleaner code, fewer bugs, and zero typo-induced runtime errors.

How to Convert JSON to Java POJO Instantly (The “No-Code” Way)