JSON to C#, Python & Dart Class Generator
Turn a JSON object or array into typed C#, Python, or Dart models with nested classes, nullability, JSON mappings, and separate-file exports.
How to use
- Paste a JSON object or array, or load one local .json file, then enter a descriptive root type name.
- Choose C#, Python, or Dart, decide whether to include language-native JSON mappings, and optionally enter a namespace or package folder.
- Generate and review the models, then copy or download the combined preview. If you need one file per class, download the ZIP archive.
Example
Input
{"id":42,"profile":{"score":4.8},"roles":["developer"],"nickname":null}
Output
A root model plus a nested Profile type, typed collections, nullable fields, and optional JSON serialization mappings.
What JSON to C#, Python & Dart Class Generator returns
JSON to C#, Python & Dart Class Generator is designed to turn a representative JSON object or array into readable typed models for C#, Python, or Dart.
Input: one valid JSON object or array up to one million characters, a root type name, a target language, an optional domain or namespace, and an optional JSON-mapping choice. Output: dependency-free C# classes, Python dataclasses, or Dart models with a combined preview, language-conventional separate files, optional namespace/package paths, and ZIP export.
How JSON to C#, Python & Dart Class Generator works
The browser parses strict JSON, walks nested values, merges object samples found in arrays, widens compatible numeric types, marks null or missing fields, and emits language-specific identifiers plus explicit key mappings.
Compile or analyze the generated file, test deserialization and serialization with more than one real payload, and compare optional fields against API documentation or a schema.
A useful situation for JSON to C#, Python & Dart Class Generator
Use it when you are starting an API client, documenting a response shape, replacing repeated map lookups, or comparing sample payload changes during integration work.
The workflow is intended for backend developers, Flutter teams, Python engineers, API testers, integration developers, and people prototyping typed clients.
Limits and common errors
Sample-based inference cannot discover undocumented variants, distinguish every semantic string type, recover precision already lost by JSON number parsing, or replace a maintained JSON Schema or OpenAPI contract.
A common mistake is treating a single successful response as the complete contract, especially when later responses may omit fields, return null, mix numeric shapes, or add new object variants.
Privacy and the next step
The JSON sample is parsed and converted locally in the browser and is never uploaded, stored, or executed by TOOLFINA.
For a broader workflow, format and validate the source JSON first, inspect Base64 fields separately, and regenerate only after comparing the new payload with existing production fixtures.
If the result matters later, keep the source payload, root type name, target language, generator settings, and a test fixture beside accepted generated code so later API changes can be reviewed.
FAQ
How does the generator decide whether a field is nullable?
A field becomes nullable when the sample contains null or when it is missing from one of several object samples in the same array. A single sample cannot reveal every future API variation, so review the result before production use.
Does generated code require third-party packages?
No. C# uses System.Text.Json attributes, Python uses standard-library dataclasses and typing, and Dart uses manual fromJson and toJson methods. You can omit mapping code when you only need declarations.
Can I download each generated class as a separate file?
Yes. Download the ZIP to get one conventionally named file per generated class. C# uses PascalCase `.cs` filenames, while Python and Dart use snake_case filenames. The optional domain becomes a C# namespace or a Python/Dart package folder inside the archive.
Is JSON to C#, Python & Dart Class Generator free to use?
Yes. The public JSON to C#, Python & Dart Class Generator runs in the browser and does not require a sign-in for normal use.
How does JSON to C#, Python & Dart Class Generator handle my input?
The JSON sample is parsed and converted locally in the browser and is never uploaded, stored, or executed by TOOLFINA.
What should I check before relying on the result?
Compile or analyze the generated file, test deserialization and serialization with more than one real payload, and compare optional fields against API documentation or a schema. Also confirm that the input reflects the exact situation you are working on.
What is a common mistake with JSON to C#, Python & Dart Class Generator?
A common mistake is treating a single successful response as the complete contract, especially when later responses may omit fields, return null, mix numeric shapes, or add new object variants. Review the original material and the final output before publishing or sharing it.
What should I use with JSON to C#, Python & Dart Class Generator?
Format and validate the source JSON first, inspect Base64 fields separately, and regenerate only after comparing the new payload with existing production fixtures. Related tools can help you check the same task from another angle.
Articles
Privacy note
Your JSON is parsed and converted locally in the browser. TOOLFINA does not upload, store, or execute the sample or generated code.
This tool runs in your browser. TOOLFINA does not require an account for public tools.