.NET Performance Analysis: Newtonsoft.Json vs System.Text.Json in .NET 8

Trevor McCubbin
5 min readJan 28, 2024
Photo by Pankaj Patel on Unsplash


As a passionate .NET developer, I find myself continuously seeking opportunities to expand my understanding of the .NET ecosystem. In this, my first article ever, I embark on a journey to explore the intricacies of .NET performance, with a specific focus on two prominent JSON frameworks: Newtonsoft.Json and Microsoft’s System.Text.Json. My goal is to share the insights and revelations gained during this exploration with fellow developers who, like me, are keen on deciphering the nuances within our tech ecosystem.

This article is inspired by Tobias Streng’s noteworthy article on .NET 7 performance and I’ve tailored my investigation to align with the latest advancements in .NET 8. Join me on this quest as we uncover the nuances between these two JSON powerhouses and gain a deeper understanding of their performance implications in real-world scenarios.

Original Article: .NET Performance #2: Newtonsoft vs. System.Text.Json by Tobias Streng

Framework Popularity

As of January 27th, 2024, Newtonsoft.Json boasts an impressive record of over 4.2 billion downloads, securing its position as the most downloaded package on NuGet. In contrast, System.Text.Json lags behind with approximately 1.8 billion downloads. Notably, System.Text.Json’s inclusion as a default in the .NET SDK since .NET Core 3.1 significantly contributes to its widespread adoption.

Comparing these numbers to the original .NET 7 article reveals a compelling narrative. At that time, Newtonsoft.Json had accumulated 2.3 billion downloads, signifying an 82.6% increase in download count over the 15-month period. In the same timeframe, System.Text.Json experienced a remarkable growth of 200%, suggesting a faster pace of adoption. However, when examining the sheer download numbers, Newtonsoft.Json added a staggering 1.9 billion downloads in this period — surpassing the total downloads for System.Text.Json since its introduction into the .NET SDK in 2019.

Benchmark Scenarios

To recreate the same scenarios as the original article, we’ll focus on two main use cases:

  1. Serialization and deserialization of a…