Which JSON library do the annotations belong to?

Jackson (com.fasterxml.jackson) @JsonProperty, which Spring Boot integrates by default. If you use Fastjson or Gson, simply delete the annotations.

Why are integers mapped to Long instead of Integer?

To avoid overflow when real data is larger than the sample suggests, integers uniformly map to the safer Long — change to Integer by hand if you prefer.

JSON to Java

Free online JSON to Java converter: generate POJOs with Jackson @JsonProperty annotations from sample JSON for Spring.

Privacy: all processing happens locally in your browser. Your input never leaves your device.

What is JSON to Java?

When a Java backend integrates with an API, you need POJO entity classes matching the JSON payload. This tool generates Java classes with Jackson @JsonProperty annotations from a sample JSON: strings map to String, integers to Long, floats to Double, arrays to List, and nested objects become separate classes. The output is ready for serialization and deserialization in Spring projects.

How to Use

Paste a sample JSON
Java entity classes are generated automatically
Copy into your project and adjust the package name

FAQ

Which JSON library do the annotations belong to?: Jackson (com.fasterxml.jackson) @JsonProperty, which Spring Boot integrates by default. If you use Fastjson or Gson, simply delete the annotations.
Why are integers mapped to Long instead of Integer?: To avoid overflow when real data is larger than the sample suggests, integers uniformly map to the safer Long — change to Integer by hand if you prefer.

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Last updated 2026-09-04