Not sure if you got the information you need but as an FYI: we published a Zimbra REST API Reference page here:
ZCS 6.0:Zimbra REST API Reference - Zimbra :: Wiki
Also, to your question about the SOAP APIs, there are a couple things to know:
- The Zimbra SOAP is the same API the zimbra web client uses to communicate with from browser-to-server. So those API interfaces include some advanced functions and are stable. As well, the API has admin commands to act on account/server data.
- You mention that SOAP API being bound to the client. You can call the SOAP API really from any client or technology you require. What might not have been clear, submitting a command to the SOAP API can handle two different formats: XML (in a SOAP envelop) and JSON.
- In the XML case, you do not need to use a client SOAP framework to for the XML, unless you want. You just need to form valid SOAP XML. We've had people even just use curl.
- If you don't want to bother with XML, you can submit in JSON format.
- The SOAP methods are documented in the ZimbraServer/docs/soap.txt and soap*.txt files. We are working to get that information online.
So the SOAP APIs aren't "REST" per se but it's a way of calling into Zimbra via URL and no external libraries required. You submit content to a URL and read a response (in either XML or JSON format).