SIM vs AIM
When involved in online sales of products or services, you need the ability to accept online payments via credit cards. The main problem that is encountered with online payments is security. Credit card numbers that fall into the wrong hands can be used unscrupulously. In order to prevent that from happening, security measures like encryption needs to be employed. For this purpose, Authorize.net provides two types of services, SIM (Simple Integration Method) and AIM (Advanced Integration Method). The main difference between SIM and AIM is that SIM redirects the user to a page on the Authorize.net server in order to collect the actual credit card number of the user. With AIM, no redirection is needed and the credit card number can be collected on the site.
Because SIM allows the credit card number to be passed on the Authorize.net site, the main site does not have to be as secure. When choosing to utilize AIM, you would need to ensure that your site is secure enough. Among other things, you need to have an SSL certificate, which identifies that the site is not a spoof.
Although SIM is rather great as it removes the complexity from your site, it does have its own drawback. Since the user is redirected to another site, there is some loss of continuity to the flow of the site. And despite the ability to configure the page, the user doesn’t have complete control of the page as it is located in the Authorize.net site. This may be enough to turn off some customers to the site and doubt its authenticity.
Both AIM and SIM works perfectly for online payments and it does not really matter much in the end. You can have either and still have a fully functional payment portal. But one can be better suited than the other for a specific site. For smaller sites, SIM is better as it can offload much of the security requirements off the site. For bigger sites, AIM is better as a higher level of security is already expected anyway. It provides a more professional feel to the site by removing the need for redirection.
AIM does not redirect the user to the Authorize.net site while SIM does
AIM requires that you have an SSL certificate while SIM does not
AIM allows for better site design than SIM
AIM is better for bigger sites while SIM is more appropriate for smaller sites