Csharp Class from JSON

Class is mutable by default (with { get; set; }) and uses reference equality. Record (C# 9+) is for DTOs – value-equality is generated automatically, comparing by property values rather than reference. For JSON DTOs that you serialize/deserialize without modifying, records are usually the better choice. Records with init-only setters ({ get; init; }) are essentially immutable.

System.Text.Json ships with .NET Core 3.0+ (no package install needed), is significantly faster, and is the modern recommendation. Newtonsoft.Json is the older standard, has more features (e.g., JsonExtensionData, custom contract resolvers), and is still widely used. The tool generates the correct attribute style for each: [JsonPropertyName] vs [JsonProperty]. They’re not interchangeable – pick to match your project’s reference.

C# 11 added required to force properties to be initialized at construction. public required string Name { get; set; } means: if you write new Foo() without setting Name, the compiler errors. Useful for DTOs where every property is mandatory. Note: doesn’t conflict with nullable annotation – required string? means “must be set, but can be null”.

int for integers up to 2^31-1 (2,147,483,647). long for integers between 2^31 and 2^53 (the limit of JavaScript’s Number precision). decimal for integers beyond 2^53 (rare). double for any non-integer (1.5, 99.99, etc.). For monetary values, you may want to manually change double to decimal in the output – JSON has no money type, so the tool can’t auto-detect.

Strings matching ISO 8601 format (2026-06-03T12:34:56Z, 2026-06-03) get typed as DateTime. For other date formats (Unix timestamps, RFC 2822) they stay as string – convert manually after deserialization. Note: DateTime doesn’t carry timezone information; for that, use DateTimeOffset (you’ll need to find/replace).

If your JSON has "data": [1, "hello", true], the elements have different types. The tool detects this and generates List<object> with a comment: // Note: source array had mixed element types. You’ll need to deserialize as JsonElement or dynamic and switch on the actual types at runtime.

JSON keys like class, namespace, return are reserved in C#. The tool prefixes them with @: public string @class { get; set; }. This is valid C# syntax. Or, combine with JsonPropertyName attribute mode to keep the JSON key and rename the C# property: [JsonPropertyName("class")] public string ClassName { get; set; }.

Plain C# source with using directives at top, optional namespace declaration, and one or more classes (one for the root + one per nested object). Indented per code-style conventions (4 spaces). Drop into Visual Studio, Rider, or VS Code with C# Dev Kit.

No. The parsing happens entirely in your browser – nothing is sent to a server, logged, or stored, and the tool keeps working offline once the page has loaded.