How to replace the server part?

Question

Java

In general, the problem is this, I'm learning to make an application something like VKontakte, sort of like I made the client part and wanted to check if everything works, but I can't do the server. Can I somehow use the same VKontakte or another social network instead of my server so that I can send an authorization request to download letters, images? Thank you.

Answer 1

https://new.vk.com/dev/openapi
log in, register, please, read api remake your application for their requests and work please, otherwise it will be necessary to remake requests for each social network that has an open api