What is the difference between Authorize.net SIM and AIM

The main differences between Authorize.net SIM and AIM are: 1) how the payment gateway is integrated into your website, and 2) what the checkout experience is like for your audience. 

With Authorize.net SIM your customers leave your website to go to a secure page to complete their order. They are then sent back to your site for a thank you page confirmation or whatever else you want to do. This is sometimes seen as "less professional" because it redirects customers away from your website and then back.This could also be argued as the more secure method of processing payments with Authorize.net because the transaction happens on the Authorize.net website within their security system and so there is less of a chance that something could go wrong.

With Authorize.net AIM: the Authorize.net's API is used to communicate between servers behind the scenes to process a sale on your own website. Your customers never leave your site and the whole process appears to be transparent. You need to have a SSL cert (which Event Smart provides for you) and all code to integrate the API. This is seen as "more professional" because people stay on your website to process their payment. There is slightly more of a risk that the transaction could fail or be compromised, but the risk is still very low given our way of securing and processing the transaction.