What is JSON to C#?
JSON to C# is a browser-based code generator that reads a JSON sample and produces matching C# classes. Nested JSON objects become nested classes, arrays of objects become List<T> properties, and each field is given a reasonable C# type based on the sample value — giving you a ready-to-paste starting point for deserializing that JSON in .NET.
When a .NET application consumes a JSON API, you typically deserialize the response into strongly-typed classes (often called POCOs or DTOs) using System.Text.Json or Newtonsoft.Json. Writing those classes by hand from an example response is repetitive and error-prone, particularly for deeply nested payloads with many properties. This tool generates the class hierarchy in one step.
The classes are inferred from the specific sample you paste, so they describe that data rather than every possible value. Everything runs locally in your browser — your JSON, which may be a real response containing sensitive fields, is never uploaded.
Why use JSON to C#?
Manually authoring C# classes for a large JSON response is slow and mistake-prone — a wrong type or a missed nested object leads to deserialization failures at runtime. Generating the classes from a real sample gives you an accurate scaffold in seconds that you can then annotate and refine.
The generator handles the structural work automatically: it names nested classes, wraps arrays of objects in List<T>, and maps primitive values to sensible C# types. That is exactly the boilerplate you would otherwise type out property by property.
Running locally protects your data. Sample API responses often contain user records, tokens, or internal identifiers you would not want to send to a third-party site. This tool processes everything in the browser and makes no network requests — verifiable in the Network tab.
Features
- Generate C# classes from any JSON sample
- Nested JSON objects become nested C# classes
- Arrays of objects become List<T> properties
- Maps primitive JSON values to appropriate C# types
- Customizable root class name
- One-click copy of the generated classes to your clipboard
- Download the result as a .cs file
- Runs entirely in your browser — no uploads, works offline
How to use JSON to C#
- Paste a representative JSON sample — ideally a real API response — into the input panel on the left.
- Optionally set the root class name (it defaults to Root) to something meaningful like ApiResponse or Customer.
- The generated C# classes appear in the right panel automatically as you type.
- Review the property types and nested classes, adjusting your source sample if the inference is off.
- Copy the classes to your clipboard or download them as a .cs file to add to your project.
Example 1 — Simple object
Paste a flat JSON object to get a single C# class with typed properties.
Input
{"name": "Ada", "age": 30}Output
public class Root
{
public string Name { get; set; }
public int Age { get; set; }
}Example 2 — Nested object becomes a nested class
Nested JSON objects are turned into their own classes and referenced as a property.
Input
{"user": {"id": 1}}Output
public class Root
{
public User User { get; set; }
}
public class User
{
public int Id { get; set; }
}Common Mistakes
- Relying on a non-representative sample: the generated classes describe only the JSON you paste. If a field is null or missing in your sample but present elsewhere, the inferred type may be wrong. Use a fully-populated example.
- Null values producing the wrong type: a field that is null in the sample gives no type information, so it may default to object or a nullable type. Substitute a real value to get the correct base type, then make it nullable if needed.
- Expecting serialization attributes: the tool generates plain classes without [JsonPropertyName] or Newtonsoft attributes. If your JSON keys do not match C# naming conventions, add the appropriate attributes yourself.
- Assuming property names match JSON keys exactly: C# properties are conventionally PascalCase, while JSON keys are often camelCase or snake_case. You may need serializer options or attributes so deserialization maps them correctly.
- Integer size assumptions: large numeric IDs may not fit in int. Check whether a value needs long (Int64) or even string, and adjust the generated type accordingly.
- Treating inferred types as validation: the class types describe shape, not constraints. A string property could hold an email or a date — the class will not enforce that.
Developer Tips
- Paste a complete API response that includes every field with realistic values so the inferred types and nested classes match what you will actually deserialize.
- Set a meaningful root class name (like OrderResponse) up front so the generated hierarchy drops into your solution without renaming.
- Add [JsonPropertyName("...")] attributes (System.Text.Json) or configure a naming policy so PascalCase C# properties map to camelCase or snake_case JSON keys.
- Change the type of large identifier fields from int to long or string in the generated code to avoid overflow with big IDs.
- Validate the JSON with the JSON Validator first — if it does not parse, it cannot be converted, and the error will point you to the problem.
Frequently Asked Questions
- How accurate are the generated C# classes?
- The classes are inferred from the JSON sample you paste, so they accurately describe that sample. Their completeness depends on your data: fields that are missing, null, or empty arrays in the sample cannot be typed precisely. For the best results, use a representative response that includes every field with realistic, populated values, then refine edge cases — such as nullable fields and large integers — by hand afterward.
- Does it add serialization attributes like [JsonPropertyName]?
- No. The tool generates plain, readable C# classes with PascalCase properties and no serializer-specific attributes. If your JSON keys use a different casing than C# conventions, you will need to add [JsonPropertyName("...")] for System.Text.Json, [JsonProperty("...")] for Newtonsoft, or configure a naming policy on your serializer so the properties map to the JSON keys correctly during deserialization.
- How are arrays and nested objects handled?
- Nested JSON objects are extracted into their own named classes and referenced as properties, keeping the output modular. Arrays of objects become List<T> properties, where T is a generated class describing the element shape. Arrays of primitives become typed lists like List<int> or List<string>. This produces the same class hierarchy you would build by hand for deserialization, but instantly and consistently.
- Is my JSON uploaded anywhere?
- No. All class generation happens locally in your browser using JavaScript. Your JSON — often a real API response containing user data, tokens, or internal identifiers — is never sent to a server, logged, or stored. You can confirm this by opening your browser's Network tab while generating: there are zero outbound requests, and the tool continues to work even offline.
- What C# types are used for JSON values?
- The generator maps JSON primitives to sensible C# types: strings become string, integers become int, decimals become double, and booleans become bool. Objects become classes and arrays become List<T>. Because the mapping is based on the sample, you should review numeric fields in particular — a large ID might need long instead of int, and a value that is sometimes null should be made nullable (for example int?) in your final code.
- Can it handle large or deeply nested JSON?
- Yes. The generator handles large, deeply nested payloads, and because everything runs in the browser, nothing is uploaded regardless of size. Large samples naturally produce many classes, which you will typically split across files and rename to match your domain model. For very large documents, generating from a trimmed but structurally complete sample yields cleaner, more maintainable class output.