I'm using https://github.com/mohiva/play-silhouette-seed I want to take from VK some data like City, country etc. but I don't know which way I should do it. It would be perfect if I can do something like this https://vk.com/dev/users.get and receive JSON which I should parse to my user's data.
With Silhouette you have two possibilities.
Social profile builders and parsers
With this you can extend an existing provider to fetch more fields and to build the data directly into your model.
This is documented in detail on the project website.
Note: The VK provider has a slightly different method signature for the parse method, because it gets the OAuth2Info passed additionally. With this you can also query the API with the Play WS API directly in the profile parser, if the data isn't already contained in the default API call. (The auth info should definitely be passed to the other providers too. I'll create a ticket for this)
Query the API with the stored access token
If you store the access token(OAuth2Info) then you can query the API with the Play WS API and merge the data into your user data.