Model REST responses
Create a starting set of Java records for an external or internal API.
100% local · files never leave your browser
Generate tool
JSON to Java Classes
Generate Java records from sample JSON in your browser, including nested objects and list types.
✓ Free to use✓ No signup✓ Runs locally
160 bytes · local only
Waiting
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Processed entirely in this tab
Your input and result are not sent to JSON Hearth or stored on a server.
When to use it
What Java Classes helps you do
Java generation turns representative JSON into a readable group of records that can be adapted for deserialization and application models.
Build test fixtures
Translate JSON examples into typed structures for unit and integration tests.
Document nested objects
Make relationships between objects and lists visible in Java source form.
How it works
Java Classes, without the upload.
Add your data
Paste a value, open a local file or begin with the working sample.
Run the tool
The transformation executes in your browser, not on our servers.
Review the result
Check the output, then copy or download it for your next task.
Important limitations
What to check before using the result
Review required
Generated records may need annotations, package declarations and framework-specific configuration.
Review required
Nullability, polymorphism and precise numeric types cannot always be inferred from a sample.
Common questions
About Java Classes
Does JSON to Java Classes upload my data?
No. Your input is processed by code running in your browser and is not sent to an application server.
Is Java Classes free to use?
Yes. The tool is free, requires no account and can be used directly in the browser.
Does the generator create records or mutable classes?
It generates Java records as a concise starting representation of the sample data.
Will the output work with every JSON library?
Library conventions differ. Add annotations or naming configuration required by Jackson, Gson or your chosen framework.