*** IMPORTANT CHANGE IN RESTSHARP VERSION 103 *** In 103.0, JSON.NET was removed as a dependency. If this is still installed in your project and no other libraries depend on it you may remove it from your installed packages. There is one breaking change: the default Json*Serializer* is no longer compatible with Json.NET. To use Json.NET for serialization, copy the code from https://github.com/restsharp/RestSharp/blob/86b31f9adf049d7fb821de8279154f41a17b36f7/RestSharp/Serializers/JsonSerializer.cs and register it with your client: var client = new RestClient(); client.JsonSerializer = new YourCustomSerializer(); The default Json*Deserializer* is mostly compatible, but it does not support all features which Json.NET has (like the ability to support a custom [JsonConverter] by decorating a certain property with an attribute). If you need these features, you must take care of the deserialization yourself to get it working.