REST - how to create custom field for given contact

Hi, I cant find this in docs https://developer.infusionsoft.com/docs/rest/#!/Contact/listCustomFieldsUsingGET

I need to create custom fields via REST API, oauth. XML-RPC docs has this explained: https://developer.infusionsoft.com/docs/xml-rpc/#data-create-a-custom-field

So, how to do this in REST API?

One more question - what’s the difference between XML-RPC API and REST oauth version? One of them is outdated, will be closed? Are the any drawbacks of using XML-RPC version?

OAuth is simply how you authenticate; we will be using OAuth for the foreseeable future, but we will retire the alternative which are Legacy API Keys at some point.

We don’t currently have a method for manipulating custom fields via REST, although as you saw, it is possible via XML-RPC. Your same OAuth Access Token will work against both APIs.

There is a legacy api key xml-rpc that will at some point, cease to exist. There is also an xml-rpc and REST implementation that both use oauth, which is the authentication method. It would be more correct to say that the use of the api key method for authentication will be dis-continued as apposed to relating that event with any api’s. You can use the xml-rpc version with oauth without concern.