JSON in C#

Serialize and deserialize JSON using System.Text.Json — JsonSerializer, [JsonPropertyName], options, handling null, unknown properties, and deserializing to generic types.

Introduction to JSON

What is JSON?

JSON is a text format for structured data — used in APIs, config files, and databases.

JSON Data Types

Supported JSON Types

JSON supports 6 types: string, number, boolean, null, array, object.

JSON Syntax Rules

JSON Rules

Keys must be double-quoted strings; no trailing commas; no comments.

Serialize Object to JSON

Basic Serialization

Convert a C# object to a JSON string with JsonSerializer.Serialize().

Pretty Print (Indented)

Produce human-readable JSON with WriteIndented = true.

Serialize a Class (POCO)

Serialize a plain C# class with public properties.

Deserialize JSON to Object

Basic Deserialization

Convert a JSON string back to a C# object with JsonSerializer.Deserialize<T>().

Nested Objects & Arrays

Deserialize JSON with nested objects and arrays into matching C# classes.

Deserialize to Dictionary

Parse JSON into a Dictionary<string, object> without a target class.

Handling Invalid JSON

Safe Parsing with try/catch

Catch JsonException to handle malformed JSON without crashing.

Handling Unknown Fields

Ignore Unknown Properties

Prevent errors when JSON has extra fields not in your C# class.

[JsonPropertyName] — Custom Field Names

Map JSON Keys to C# Properties

Use [JsonPropertyName] to map snake_case JSON keys to PascalCase C# properties.

Global camelCase Policy

Apply camelCase to all property names using JsonNamingPolicy.

Deep Cloning with JSON

Deep Clone via Serialize → Deserialize

Create a fully independent copy of an object by round-tripping through JSON.

Validating a JSON String

Check if a String is Valid JSON

Use JsonDocument.Parse() inside a try/catch to validate JSON syntax.

Safe Parse Helper

Return a result object instead of throwing — ok/error pattern.