Per provider, this API will be deprecated in January 2019. Developers are encouraged to migrate to the Google Photos Library API
From their site: The Picasa Web Albums data API allows client applications to view and update Picasa Web Albums content in the form of Google data API GData feeds. Your client application can request a list of user albums, photos, comments, or tags, edit or delete content in an existing entry, and query the content in an existing entry.
The following is a list of how-to and tutorial content that matched your search term. ProgrammableWeb's how-to content comes from two sources; full-blown tutorials that we publish ourselves and other highly relevant tutorials that we find elsewhere on the Web. This list represents on combination of both tutorial types and if you go to ProgrammableWeb's API University, you'll not only be able to find more, they are organized based on your role (API providers or developers who consumes APIs). If you know of a tutorial that would be of interest to the ProgrammableWeb community, we'd like to know about it. Be sure to check our guidelines for making contributions to ProgrammableWeb.