JSON to Java Class Generator
Generate Java classes with Jackson annotations from JSON samples.
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Your result appears here
Paste JSON into the panel on the left — everything runs privately in your browser.
Overview
JSON to Java Classes — Generate POJOs Online
Generate Java classes (POJOs) from a JSON sample. Paste an API response and get typed fields with nested classes for embedded objects — the scaffolding you need before deserializing with Jackson or Gson. Type inference handles strings, numbers, booleans, arrays, and nested structures, so you skip the tedious boilerplate. Runs locally in your browser, ideal for modeling private or third-party payloads.
How the generator infers types
Each JSON value maps to a Java type: strings to String, whole numbers to int or long, decimals to double, booleans to boolean, and objects to their own nested class. JSON arrays become List<T>, with T inferred from the elements. A root class wraps the top-level object, and every nested object becomes a separate named class.
The output gives you fields with appropriate types; getters and setters are omitted by default so the result stays compact — add them with your IDE or Lombok as your project conventions require.
Why generate POJOs from JSON
- Avoid hand-writing classes for large or deeply nested responses
- Gain compile-time safety and IDE autocomplete over raw JSON
- Model undocumented APIs quickly from one representative sample
- Keep your data classes aligned with the real payload shape
Refining the generated classes
Types come from a single example, so review them before production use. Add Jackson annotations like @JsonProperty when JSON keys differ from Java field names, widen int to long where large values are possible, and wrap optional fields appropriately. Need a different language? Use the matching TypeScript, Go, Python, or C# generators.
FAQ
Frequently asked questions
Does it generate getters and setters?
By default the output focuses on typed fields and omits getters and setters to stay readable. Generate them with your IDE, or use Lombok's @Data to add them automatically.
Which JSON library should I use?
The POJOs work with both Jackson and Gson. Add library-specific annotations only when JSON key names differ from your Java field names.
How are nested objects represented?
Each nested JSON object becomes its own named Java class, producing a full type hierarchy instead of generic maps.
Is my data private?
Yes. Generation runs entirely in your browser; your JSON is never uploaded, making it safe for internal or proprietary data.
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