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Convert JSON data into Crystal class definitions and automatically generate type-safe serialization code.
When you need to convert JSON API responses or configuration data into type-safe classes in the Crystal language, manually writing field mappings and type declarations is both tedious and error-prone. This tool parses your input JSON string, automatically infers field types and nested structures, and generates Crystal class or struct code with JSON::Serializable support. The core processing object is a JSON-compliant data structure, and the output is Crystal class definition code that can be directly embedded into your project.
How does the JSON to Crystal converter handle null fields?
The tool infers null values in JSON as the Nil type, generating nullable type declarations like property name : String? to ensure type safety.
What if the input JSON format is invalid?
The system will prompt a JSON parsing error and abort the conversion. Please use an online JSON validator to check the validity of your data format first.
Please ensure the input is in standard JSON format. Complex nested structures may require manual adjustments to the generated type annotations. The generated code does not include custom method logic, which developers will need to add based on business requirements. All processing is done locally in your browser; your JSON data is never sent to a server.
For scenarios requiring precise control over serialization behavior, we recommend manually adding JSON::Field annotations after generating the code. For example, use @[JSON::Field(key: "originalName")] to maintain the mapping with the original JSON field. Typical input/output example: Inputting {"userName":"Alice","age":25} will generate the class definitions property user_name : String and property age : Int32.