json to c# record & class converter
typetools
instant, client-side type converter • 0ms network latency
using System.Collections.Generic;
using System.Text.Json.Serialization;
namespace App.Models;
public sealed record Metadata(
[property: JsonPropertyName("lastLogin")] string LastLogin,
[property: JsonPropertyName("ipAddress")] string IpAddress,
[property: JsonPropertyName("failedAttempts")] object? FailedAttempts
);
public sealed record RootPayload(
[property: JsonPropertyName("userId")] string UserId,
[property: JsonPropertyName("username")] string Username,
[property: JsonPropertyName("email")] string Email,
[property: JsonPropertyName("isActive")] bool IsActive,
[property: JsonPropertyName("score")] double Score,
[property: JsonPropertyName("roles")] IReadOnlyList<string> Roles,
[property: JsonPropertyName("metadata")] Metadata Metadata,
[property: JsonPropertyName("tags")] IReadOnlyList<object> Tags
);step-by-step integration guide
technical specification differences & end-to-end conversion workflow
High-Performance Deserialization in .NET 8+ with System.Text.Json and C# Records
Modern .NET 8 and C# 12 applications favor immutable record types and the UTF-8 span-based System.Text.Json serializer over legacy reflection-heavy Newtonsoft.Json classes. Unlike JavaScript or Python dictionaries, C# enforces PascalCase property naming conventions (UserId, CreatedAt) and strict nullable reference types (#nullable enable). When System.Text.Json.JsonSerializer.Deserialize<T> processes an incoming UTF-8 byte stream, case-sensitive property matching is enabled by default for performance, meaning a camelCase or snake_case JSON key will fail to bind to a C# PascalCase property unless decorated with an explicit [JsonPropertyName("...")] attribute.
Synthesizing [JsonPropertyName] Attributes, Nullable Value Types, and IReadOnlyList
Our JSON-to-C# converter traverses your JSON payload and emits idiomatic C# definitions. Every JSON key is converted to a clean PascalCase C# identifier while preserving its exact original wire name inside a [JsonPropertyName("wire_key")] attribute from System.Text.Json.Serialization. The AST inference engine inspects numeric magnitudes to choose between int, long (Int64), and double/decimal, and detects ISO-8601 date strings to infer DateTimeOffset. When a field is nullable or optional across array elements, the generator appends the C# nullable suffix (string?, int?, bool?), ensuring full compatibility with C# Nullable Reference Types (NRT) and Source Generation contexts (JsonSerializerContext).
frequently asked questions
common developer questions answered
q:Why should I use C# records instead of traditional POCO classes for JSON DTOs?
C# records provide built-in value-based equality, non-destructive mutation via 'with' expressions, concise positional syntax, and immutability out of the box—ideal for API Data Transfer Objects (DTOs).
q:Are the generated C# types compatible with .NET Native AOT and System.Text.Json Source Generators?
Yes. Because every property uses standard System.Text.Json.Serialization [JsonPropertyName] attributes and concrete generic collections, you can register the root type directly in a [JsonSerializable] context for zero-reflection Native AOT builds.
q:Why does the converter use DateTimeOffset instead of DateTime for ISO-8601 timestamps?
DateTimeOffset preserves the exact UTC offset from the ISO-8601 JSON string and avoids ambiguous local-vs-UTC timezone conversion bugs inherent to System.DateTime.