Hi Oleg,
It would be great to have a REST API plugin. We have already today in the Internet plugin the Action "Check HTTP address", but perhaps we could have more options, like HTTP verb (not only GET), Authentication (can be done with headers, but it is just all more difficult), etc.
Also as part of the plugin we could have an action to parse the response. We already have JS capabilities, but perhaps something more specifically to handle mainly JSON objects and arrays, and also error messages of the REST API call, HTTP codes, etc.
This would be a big complex plugin, but it could be done one step at a time in different releases.
Kind regards,
Juanlu.