What is a JSON to Java converter?
Hand-writing classes for an API response is slow and error-prone. This tool infers Java classes from a JSON sample: nested objects become named types, arrays become typed collections, and null/missing values become optional fields. It runs quicktype's inference engine entirely in your browser, so real API payloads (often containing user data or credentials) never leave your machine.
Java mapping notes
- POJOs with getters/setters; field names convert to camelCase.
- Numbers map to
long/double; nullable values use boxed types. - Works directly with Jackson/Gson; annotations can be added on top.
How to use
- Paste a JSON sample (an API response works well) into the Input pane.
- Generated Java classes appear instantly. Nested objects become their own named types.
- Non-standard JSON (single quotes, trailing commas, comments) is auto-repaired first.
- Copy the code into your project.
Examples
JSON → Java classes
{
"id": 42,
"name": "workbench",
"owner": { "email": "[email protected]", "active": true }
}public class Root {
private long id;
private String name;
private Owner owner;
// getters & setters
}FAQ
How do I convert JSON to Java types?
Paste any JSON sample. The classes are inferred from the values and nesting, entirely in your browser. Nothing is uploaded.
How are nested objects handled?
Each distinct nested object becomes its own named type, referenced from the parent, arrays of objects included.
What about optional or null fields?
Fields that are null or missing in parts of the sample are typed as optional/nullable in the generated code.
Can I paste multiple samples?
Paste an array of objects: the type is inferred from the union of all items, which catches optional fields a single sample would miss.
Records instead of classes?
Output is classic POJOs for maximum compatibility; converting simple ones to Java 17 records is mechanical.
Is my JSON uploaded?
No. Generation runs 100% in your browser via quicktype's engine. Check DevTools: zero network requests.