I recently stumbled across a comparison of JSON serialization libraries. which shows that ServiceStack.Text by far outperforms any of the competitors. Indeed, the folks down at ServiceStack have been building a lot of great stuff for the past few (4?) years to facilitate their framework. ServiceStack.Text is available on Nuget and can be used outside of ServiceStack, within any .NET project, so why not use it with Web API, replacing the default serializer, JSON.NET?