JSON to C#

JSON to C# turns an API response or any JSON sample into C# types in one file with a file-scoped namespace. Class mode writes { get; set; } properties; Record mode writes positional records and places attributes on the generated properties with [property: ...]. System.Text.Json uses [JsonPropertyName("key")] and Newtonsoft.Json uses [JsonProperty("key")]. A property never gets its enclosing type's name, which C# does not allow.

1. 1.Paste JSON, upload or drop a .json file, or load one of the examples.
2. 2.Set the root type name and optional namespace such as Company.Project.Models.
3. 3.Choose the type style, property naming and nullable reference types.
4. 4.Choose the serializer and attribute policy, then copy the code or download <Root>.cs.

• •Every array item is inspected, not just the first one, and objects in the same array are merged.
• •A key missing from some objects is optional; a key that is sometimes null is nullable. The two are kept apart.
• •1 and 2.5 in the same position widen to a decimal number; other mixes are reported.
• •Empty arrays and values that are only ever null have no type evidence, so a generic type is used and a note explains why.
• •Type mapping: string → string, integer → int, long, ulong or decimal by range, decimal → double, boolean → bool, array → List<T>, object → class or record, missing or null → T?, unknown or mixed → object.
• •Required members need C# 11 / .NET 7 or later; System.Text.Json then rejects JSON that misses a required key.

A sample shows what the data looked like once, not the full API contract. Review optional fields, generic types and number widths before relying on the code. Input is limited to 5 MB and 256 nesting levels; from 2 MB, generation waits for the Generate button. Everything runs in your browser and the JSON is never uploaded. With System.Text.Json, object properties hold a JsonElement after deserialization.