JSON to C# Classes — The .NET Developer's Shortcut
If you're building .NET applications, you're probably using System.Text.Json or Newtonsoft.Json for JSON deserialization. Both libraries work best when you have strongly typed C# classes that match your JSON structure. Writing those classes by hand is fine for small payloads, but when you're dealing with an API that returns 30 nested fields, it gets tedious fast.
This tool generates clean C# classes with auto-properties (the { get; set; } pattern) and PascalCase naming that follows .NET conventions. Nested objects get their own class definitions. Arrays become List<T> with the correct generic type. It's exactly what you'd write yourself — just without the manual copying of field names.
System.Text.Json vs Newtonsoft.Json
Starting with .NET Core 3.0, Microsoft ships its own JSON library. It's faster than Newtonsoft for most operations and doesn't require a NuGet package. The generated classes work with both libraries out of the box. If you need [JsonPropertyName("original_key")] attributes for kebab-case or snake_case JSON keys, you can add them to the generated class — the property structure is already there.
Nullable Types in C# JSON
Modern C# (8.0+) has nullable reference types. When your JSON has fields that might be null, you'll want to add ? to the property type. The generated code gives you a solid base — you can then make fields nullable as needed based on your API's actual behavior. It's much easier to start with a complete class and make things optional than to build from scratch.
ASP.NET API Integration
In ASP.NET Web API controllers, you often need DTOs (Data Transfer Objects) that match incoming or outgoing JSON. Grab the actual JSON payload from Postman or your browser's DevTools, paste it here, and get your DTO in seconds. Add [Required] attributes for validation, hook it up to your controller, and you're done. Beats writing boilerplate DTO code for every endpoint.
Real-World Usage Tips
For large APIs, generate your classes from the most complete response you can find — one that includes all optional fields populated. This gives you the full class structure. Then mark potentially-absent fields as nullable. Also consider using records (public record) instead of classes for immutable DTOs in .NET 5+ projects.
Related JSON Tools
Need frontend types for your Blazor or React frontend? Generate TypeScript interfaces from the same payload. For API validation, create JSON Schema definitions. Compare JSON responses between API versions.