User Defined TypeSelectors Creating your own TypeSelector is a relatively easy process. Essentially all you need to do is: Create your your class that inherits from ITypeSelector Implement the CheckType function Add an instance of your class to the TypeSelectors of the that you are going to use when loading your classes that should take advantage of your TypeSelector. Example For our example we are going to build on the TypeSerializerUserDefined example. In that example, we made a TypeSerializer that will serialize an int into a three byte array and then deserialize three bytes into an int. For our TypeSelector we will assume that any property that has a type of int and whose name starts with ThreeByte should use the TypeSerializerThreeByteNumeric that we defined in the other example. Our TypeSelector can be implemented as shown below. Note that when your TypeSelector does not know how to handle the property it should return null so that any further TypeSelectors can be checked. public class TypeSelectorThreeByteNumeric : ITypeSelector { public Type CheckType(MessageSerializedPropertyInfo propertyInfo) { if (propertyInfo.PropertyInfo.PropertyType == typeof(int) && propertyInfo.PropertyInfo.Name.StartsWith("ThreeByte")) { return typeof(TypeSerializerThreeByteNumeric); } return null; } } Make sure you are returning the TypeSerializer and not the TypeSelector. Now you need to add your TypeSelector to the TypeSelectors list of the and then use those SerializationDefaults when loading whatever class that you want your TypeSelector to apply to. Note that in the code below our new TypeSelector is put into the list first. The reason for this is that it has to be put before TypeSelectorNumeric as TypeSelectorNumeric will match with an int property and if our TypeSelector was at the end of the list its CheckType would never be called because the property was already matched. var serializationDefaults = new SerializationDefaults(); serializationDefaults.TypeSelectors.Insert(0, new TypeSelectorThreeByteNumeric()); _classInfo = Serializer.Instance.GetClassInfo(typeof(TestClass), serializationDefaults);