Microsoft’s System.Text.Json is the future for high-performance, modern cloud-native apps. But Newtonsoft.Json is the reliable, duct-tape-and-ingenuity library that still holds vast swaths of the .NET ecosystem together. It didn't just solve JSON serialization—it defined it.
| Feature | Newtonsoft.Json | System.Text.Json | |---------|----------------|------------------| | Default property name casing | Preserved | camelCase | | Non-public members | Can serialize with opt-in | Not supported | | Dictionary with non-string keys | Serializes as JSON object | Throws or requires converter | | Cyclic references | ReferenceLoopHandling.Ignore | Not supported | | DateTime handling | ISO by default | Strict ISO (no legacy formats) | newtonsoft json dll
var settings = new JsonSerializerSettings Microsoft’s System
Even with Microsoft's own System.Text.Json now baked into the platform, Newtonsoft.Json remains deeply embedded in countless production systems, legacy projects, and even modern greenfield development. Why? Because it’s battle-hardened, absurdly flexible, and packed with features that feel like magic. | Feature | Newtonsoft
In the sprawling universe of .NET development, few third-party libraries have achieved the ubiquity and lasting influence of Newtonsoft.Json (also known as Json.NET). For over a decade, it has been the default, instinctive choice for handling JSON—whether you were building a tiny console app, a massive enterprise web API, or a cross-platform mobile backend with Xamarin.
So pour one out for the DLL that refused to die. And then maybe add a reference to it, because your appsettings.json file still needs parsing. Have a Newtonsoft war story? A custom converter that saved your bacon? Share it in the comments below.
public override void WriteJson(JsonWriter writer, DateTime value, JsonSerializer serializer) => writer.WriteValue((value - new DateTime(1970, 1, 1)).TotalSeconds); public override DateTime ReadJson(JsonReader reader, Type objectType, DateTime existingValue, bool hasExistingValue, JsonSerializer serializer) => new DateTime(1970, 1, 1).AddSeconds(Convert.ToDouble(reader.Value)); You don't always have a strongly-typed class. Sometimes you need to parse, query, or modify JSON on the fly. Newtonsoft’s JObject lets you treat JSON like an XML DOM.