Official comment
We have two APIs available, a legacy XML style API, and then a more object orientated one we call our New API. Both are still supported fully.
You can see an overview at our API In ONTRAPORT article.
That article has all the links to example code, and instructions on using the new interactive object orientated API documentation.
A Note About "Custom Coding" Support: We cannot assist you in learning how to program using the API. But for those of you already coding, we are happy to help with specific questions about code you have written that is producing an error. Please include the code in a plain text file and attach it to an email to api@ontraport.com. Include a description of the error you are receiving. One of our developers will respond to your request during normal business hours.