Checkout API tutorial on O’Reilly network
January 17th, 2007 | Published in Google Checkout
The O'Reilly Network has published my tutorial about the Google Checkout API, and you can read it here: Build a .NET App for Google Checkout.
Though the code samples in the article are for .NET, I think it's a good overview of the API and a good read for anyone planning to integrate Google Checkout into their online store. The article demonstrates level 1 and level 2 integrations.
For more code samples in various languages, visit our samples page.