How to add a custom field with Magento 2 REST API

Hi, I need to add a value from my database to Magento’s Customer table. I been reading about custom attributes and how that extends functionality in Magento Entities but what I need to do is to add a custom field using the REST API.

What I want to accomplish is to find a way to call the existent API and just make a POST request to extends the functionality (add a new custom field ) of the customer entity to add a field and value from my Customer information. For example, if my customer entity have a field named xyz I want to find a way to add that field name also in Magento’s customer table and it’s value.

I’m completely new in Magento so I don’t know If that is possible, thanks!

Note: I want to do it this way because I don’t want to touch the system! I don’t want to code the functionality

Hi Dmitry thanks for your quick replay! I’m seeing the links that you posted and It seems that there is no way to do what I’m trying to do without code, Am I correct?