Sage 300 is available in 3 options:
This is the classic offering of Sage 300. It is desktop based and usually deployed as an on-premise solution.
This is a new option from Sage that offers a full fledged solution that is both desktop as well as browser based. As with the classic Sage 300, it is an on-premise solution, however, it is on a subscription model which makes it more affordable and accessible to smaller businesses.
Sage 300 Online is a full fledged SaaS based solution that is hosted by Sage. It is browser based.
Sage 300 solutions can be further enhanced and adapted by third party add-on solutions. These are developed by Sage Endorsed Development partners. The solutions are developed within the Sage 300 SDK (Software Development Kit) and work seamlessly within Sage 300 itself.