Contextly can work with enterprise and custom content management systems. We have a very simple way for enterprise sites to use Contextly.
If you are interested, please drop us a note at email@example.com and we can get you that documentation.
We currrently do not support SquareSpace, Blogger, Wix or HubSpot -- though we'd like to. These are proprietary systems that we either need permission to work with in order to get the meta-data we need, or are simply systems we haven't had time to support yet.
If you work with another system, feel free to drop us a note at firstname.lastname@example.org