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POJO to JSON

Generate a JSON template from a Java class. Each field becomes a key with a sensible default for its type. Good for seeding API fixtures, mocks, and Postman collections.

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How It Works

  1. 1

    Paste Java class

    Just the class body. Fields, modifiers, types. Methods are ignored.

  2. 2

    Fields are mapped

    Each field becomes a JSON key with a sensible default for its type.

  3. 3

    Copy template

    Use the JSON as a starting fixture for tests, mocks, or API examples.

Use Cases

  • API contract fixture

    Generate a starting JSON example from your Spring controller's request DTO.

  • Postman / Bruno collection seed

    Drop the generated JSON into a request body to start manual testing.

  • Mock server payload

    Use the template as a Wiremock or Mirage stub response.

  • Documentation sample

    Paste the JSON into API docs as an example payload.

Frequently Asked Questions

It takes a Java POJO (Plain Old Java Object) class declaration, extracts its fields, and emits a JSON template populated with sensible default values per Java type. Use it to generate a request body fixture or a starting JSON sample from a class definition.
Standard field declarations like `private Type name;` or `public Type name;`, with optional `static`, `final`, and initializers. Common primitive and boxed types (int, Long, double, boolean, String), date types (LocalDate, Instant, etc.), and collection types (List, Set, Map) all get appropriate JSON defaults.
Not yet — this tool goes one direction (POJO → JSON template). For the reverse (JSON → POJO class), use jsonschema2pojo or your IDE's built-in generator (IntelliJ has `Edit → Paste Special → Paste JSON as Classes`). We may add JSON → POJO here if there's demand — let us know at support@bug0.com.
Unknown reference types are emitted as `{}` placeholders. Paste each nested class separately to drill into them, or hand-edit the output.
No. It uses a focused field-declaration regex, not a full Java parser. Methods, constructors, annotations, and inner classes are ignored. Good enough for the common case of generating JSON from a data class.
Partially. Lombok-annotated classes still have explicit field declarations and work fine. Kotlin data classes use a different syntax (`val name: Type`) and are not supported.
No. Parsing runs entirely in your browser.

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