Samples for the Google Photos Library API are available from the Google Photos sample repository on GitHub. In addition, you can find code snippets on each page of this developer's guide.
Samples on GitHub
The GitHub repository contains a sample that shows the search and list functionality of the Library API as implemented in an online photo frame using Node JS.
The GitHub repositories for each client library contain multiple samples that show how to use the Library API in different languages.
If you're having trouble using the samples, make sure that you've done the following:
The OAuth credentials need to be added to the sample project. For details, see the README.
Code snippets in the developer's guide
Each page in the developer's guide includes code snippets and REST calls that illustrate particular features of the API. Some of the guides available for features include the following: