I know that there is an older post here with the same question. But it was asked in 2012 and the answers are also a couple of years old. Also that is about Google+ Photos, and I am asking about Google Photos
Recently Google Photos has been made a shiny new service with new announcements about having unlimited photo uploads (for photo size < 16 MB). I am currently having a service that uploads to Google Drive. I checked Google Developer site but did not find anything related to Google Photos.
So does the new Google Photos have any open API with it? Does anyone have any information? I appreciate your input.
Yes and no.
Yes, because uploading/dowloading/creating albums via the old Picasa Web Data API will have changes reflected to the new Google Photos interface as well.
No, because regardless of the user setting, all photos uploaded through this old API will count against the user's storage quota (even if you upload using the desktop version of Picasa!).
The Google Photos backup tool does some pre-compression before uploading photos, and only this (proprietary, undocumented) way of communicating with Google's servers provides access to the unlimited storage.
来源：https://stackoverflow.com/questions/30690535/is-there-a-google-photos-api