Introduction
In modern .NET applications, JSON serialization and deserialization are critical for handling data exchange. Microsoft introduced System.Text.Json as a high-performance alternative to Newtonsoft.Json, which has been the standard for years. This article explores the key differences, performance benchmarks, and use cases for both libraries to help you choose the best option for your project.
1. Overview
System.Text.Json (Introduced in .NET Core 3.1+ and .NET 5+)
- Built-in JSON serializer for .NET Core and .NET 5+.
- Optimized for performance and low memory usage.
- Lacks some advanced features available in Newtonsoft.Json.
Newtonsoft.Json (Also known as Json.NET)
- A widely used third-party library for JSON processing.
- Rich feature set, including JObject, LINQ-to-JSON, and custom converters.
- Supports older .NET Framework versions.
2. Performance Comparison
Performance is one of the primary reasons Microsoft introduced System.Text.Json. It is designed for high-speed serialization/deserialization and lower memory overhead.
| Feature |
System.Text.Json |
Newtonsoft.Json |
| Serialization Speed |
🚀 Faster (Optimized for .NET) |
⚠️ Slower due to additional features |
| Memory Usage |
✅ Lower |
❌ Higher |
| Deserialization Speed |
✅ Faster |
⚠️ Slightly slower |
| Case Sensitivity |
❌ Case-sensitive by default |
✅ Case-insensitive |
| CamelCase Support |
⚠️ Requires JsonSerializerOptions |
✅ Enabled by default |
🔹 Verdict: If performance is your priority, System.Text.Json is the better choice.
3. Feature Comparison
While System.Text.Json offers speed and efficiency, it lacks some advanced features that Newtonsoft.Json provides.
| Feature |
System.Text.Json |
Newtonsoft.Json |
| Built-in Support |
✅ Yes (part of .NET) |
❌ Requires NuGet package |
| LINQ-to-JSON (JObject) |
❌ Not available |
✅ Fully supported |
| Dynamic JSON (JToken) |
❌ Not supported |
✅ Fully supported |
| Custom Converters |
⚠️ Limited |
✅ More powerful |
| Reference Handling |
⚠️ Limited |
✅ Supports circular references |
| JSON Comments |
❌ Not supported |
✅ Fully supported |
| Serialization Formatting |
✅ WriteIndented = true |
✅ Formatting.Indented |
🔹 Verdict: If you need dynamic JSON handling or custom serialization rules, Newtonsoft.Json is more flexible.
4. Code Examples
Using System.Text.Json (Recommended for performance)
using System.Text.Json;
var json = JsonSerializer.Serialize(myObject);
var obj = JsonSerializer.Deserialize<MyClass>(json);
✅ Optimized for .NET Core and .NET 5+.
🔹 Handling case insensitivity.
var options = new JsonSerializerOptions
{
PropertyNameCaseInsensitive = true
};
var obj = JsonSerializer.Deserialize<MyClass>(json, options);
Using Newtonsoft.Json (For complex JSON needs)
using Newtonsoft.Json;
var json = JsonConvert.SerializeObject(myObject);
var obj = JsonConvert.DeserializeObject<MyClass>(json);
✅ Supports LINQ-to-JSON and dynamic JSON manipulation.
🔹 Working with dynamic JSON.
JObject jsonObj = JObject.Parse(json);
string value = jsonObj["someKey"].ToString();
5. When to Use Which?
✅ Use System.Text.Json when.
- You need high performance and low memory usage.
- You are working with ASP.NET Core or Blazor (it's the default JSON library).
- You don’t need advanced JSON features like JObject.
- You want built-in support without extra dependencies.
✅ Use Newtonsoft.Json when.
- You need dynamic JSON handling (JObject, JToken).
- You work with complex or deeply nested JSON structures.
- You require custom converters, reference handling, or advanced settings.
- You need support for legacy .NET Framework versions.
6. Conclusion
Both System.Text.Json and Newtonsoft.Json have their strengths and weaknesses. If performance is your top priority, System.Text.Json is the way to go. However, if your project requires advanced JSON processing, Newtonsoft.Json remains the best choice.
🚀 Recommendation: Use System.Text.Json for new .NET Core/ASP.NET Core projects and switch to Newtonsoft.Json only when you need advanced features.
Which one do you prefer for your projects? Let us know in the comments!