C# serialization like newtonsoft for android and ios

Does anyone have experience with serialization and deserialization from json on these platforms?
Newtonsoft has made it easy on .net (others too). I thought I’d ask before trying to create something.
I’m trying to make ios and android clients to read/write to a webserver’s rest services as easily as a WPF application does.

Right now, on our side we only have the cross-platform JsonDocument in Elements RTL, which does reading and writing of JSON, but not automatic (de)serialization. We are looking at doing Swift-style language level en/decoding, but that’s a more long term project (ie now this month, probably not next).

There might (probably will) be third party libraries out there for Java and iOS that can be used, but I;'m not familiar with any that I could recommend.