Ready to generate
Paste JSON and click Generate C# Classes// generate C# POCO classes from JSON instantly
Convert JSON to C# POCO classes instantly. Generate clean, typed C# models with proper data annotations for faster API integration and .NET development.
Ready to generate
Paste JSON and click Generate C# ClassesPaste your JSON object or array into the input area on the left.
Set your root class name, namespace, and toggle options like nullable types or data annotations.
Click Generate — your C# POCO classes appear on the right, ready to copy into your project.
This tool converts any valid JSON structure into C# POCO (Plain Old CLR Object) classes. It analyzes your JSON, infers types, handles nested objects and arrays, and generates clean, ready-to-use C# code compatible with .NET, ASP.NET Core, and any modern C# project.
POCO stands for Plain Old CLR Object. It's a simple C# class with no dependencies on any framework — just properties and fields. POCOs are ideal for representing data models, API responses, and DTOs because they're lightweight and portable across any .NET project.
Yes. The generator recursively processes nested JSON objects and creates a separate C# class for each one. The parent class references the nested class by name, giving you a clean, typed class hierarchy that mirrors your JSON structure.
JSON arrays of objects become List<T> properties, where T is a generated class. Arrays of primitives become List<string>, List<int>, etc. The tool inspects the first element to determine the item type.
When enabled, the generator adds [JsonProperty("originalName")] attributes (Newtonsoft.Json) above each property. This is useful when your JSON keys use camelCase or snake_case, but you want PascalCase property names in C# — the attribute maps them correctly during serialization.
Data Annotations are attributes from System.ComponentModel.DataAnnotations used for model validation. When enabled, this tool adds common ones like [Required] for non-nullable string fields. They're used by ASP.NET Core for automatic model validation in API controllers.
No. All processing happens entirely in your browser using JavaScript. Your JSON never leaves your machine — there are no server calls, no logging, and no data storage. This makes the tool safe for use with sensitive or private JSON payloads.
The tool maps JSON types to C# types: string → string, integer numbers → int or long, decimal numbers → double, booleans → bool, null → nullable variants, objects → generated classes, and arrays → List<T>.
The generated POCOs work with both serializers. If you use System.Text.Json, you can replace [JsonProperty] with [JsonPropertyName] from System.Text.Json.Serialization. The class structure itself is identical for both libraries.
When building APIs, integrating third-party services, or working with configuration data in .NET, you constantly need to map JSON structures to C# classes. Doing this manually is tedious, error-prone, and time-consuming — especially with deeply nested or large payloads. This free JSON to C# class generator automates the entire process, giving you clean, typed POCO classes in seconds.
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A well-generated C# class from JSON should preserve the semantic meaning of your data while following C# conventions. That means:
FirstName not firstNameSince C# 8.0, the language supports nullable reference types, where you opt into non-nullable by default. This is now enabled by default in .NET 6+ projects. When the nullable option is enabled, this generator marks reference types that might be absent as string?, ChildClass?, etc., giving you precise null-safety annotations that integrate with the compiler's flow analysis.
If you're building an ASP.NET Core API, data annotations let you declare validation rules directly on your model properties. The [Required] attribute tells the model binder that a field must be present; [MaxLength], [Range], and others constrain values. ASP.NET Core will automatically return a 400 Bad Request if a posted JSON body violates these rules, without you writing any manual validation code.
The .NET ecosystem has two major JSON serializers. Newtonsoft.Json (Json.NET) was the de-facto standard for years and is still widely used. It uses [JsonProperty("name")] for property mapping. System.Text.Json is the built-in serializer added in .NET Core 3.0+, with [JsonPropertyName("name")] for the same purpose. The POCO classes generated by this tool work with both — the class structure is identical. Only the attribute namespace differs if you use the [JsonProperty] option.
Once you have your generated classes, using them is straightforward. With System.Text.Json:
var result = JsonSerializer.Deserialize<RootObject>(jsonString);
Console.WriteLine(result.Name);With Newtonsoft.Json:
var result = JsonConvert.DeserializeObject<RootObject>(jsonString);
Console.WriteLine(result.Name);Both approaches give you fully typed access to your JSON data with IntelliSense, null-safety, and compile-time checking.
EF Core 7+ supports JSON columns natively. You can store complex JSON objects in a single database column and map them to C# classes using OwnsOne or OwnsMany in your DbContext. The POCO classes generated here are immediately compatible with this pattern — no base class or interface required.
When using generated classes in production, consider these best practices: keep models in a dedicated Models or Dto folder/namespace; avoid mixing business logic with data models; use records for immutable response DTOs in C# 9+; and consider using AutoMapper or Mapster to convert between your API models and domain entities rather than using the same class throughout your application stack.
Manually writing C# classes from JSON is straightforward for small payloads, but quickly becomes impractical. A response from a real-world API like Stripe, GitHub, or Shopify can have 50+ fields across 10+ nested objects. Typing those by hand takes 20-30 minutes, introduces typos, and requires constant cross-referencing with the raw JSON. This generator does it in under a second, with consistent naming, proper types, and all the attributes you need — letting you get back to the actual work.