WebsitePanel was one of the open source Windows hosting control panels. It was widely used by web hosting providers to provision shared hosting service, VPS and private Cloud.
All of sudden, development was stopped and the users were left with no option other than to find alternative solution to migrate from WebsitePanel. After last release of WebsitePanel 2.1, the development was stopped and there will not be any future release available for WebsitePanel. That means the bugs which exist in WebsitePanel 2.1 will never be fixed.
There were two separate groups using WebsitePanel fork to develop and maintain their own control panels. Also, there is a possibility to migrate your WebsitePanel installation to those control panels. We will discuss in detail for both control panels.
SolidCP is using WebsitePanel fork to develop their control panel. They are providing open source control panel. That means, you can view and modify source as per your need if you wish. Also, this is completely free web hosting control panel for Windows server.
SolidCP includes all features which was supported by WebsitePanel 2.1. In addition to this, they support SQL 2016 server as well as they have fixed lots of bugs which were present in WebsitePanel 2.1. If you are looking for free WebsitePanel alternative, SolidCP is a good start for you.
MSPControl is also using WebsitePanel source. But this is not completely free. For shared hosting setup, most of the features are free and you can use it however there is no guarantee that it becomes paid in future. You may contact their sales to clarify this. Also, this is not an open source control panel hence you will not have full control on the source code of the control panel.
To check for the available paid addons, you can refer their website for more information or you may contact their sales team.
You can also go for Plesk control panel. Please understand that there will not be direct way to migrate your websites and data from WebsitePanel to Plesk. It will be manual migration.
Plesk is a commercial web hosting control panel for Windows and Linux server. If you go for Plesk, you will not be able to migrate your websites and other data directly. You will have to do manual migration. This is also a best alternative to WebsitePanel.
This article is just for information purpose only. Before you go for any WebsitePanel alternative, make sure you thoroughly test it.