For Apple phone systems most of the applications can be downloaded for free from:
Apple store: 
Such as TUYA, HDLiveCam, CamSC Pro, Allcam365, Ubox, Etc.
For Android base phones you can download the same applications from:
Google Play Store:
Keep in mind that from time to time the application developers will upgrade, change or even discontinue these from these platforms because of some security issues or specific requirements that can't be met, on this last, the developers will find an alternative way to provide you the download for the application through platforms such as:
APKPure 
Alternatively, we will post here the direct links for the applications that have moved away from the standard Apple or Google platforms.
The following are alternative links to the applications listed below:
HDLiveCam For android phones you will have to download APKPure platform in order to download the application, or alternatively use the following link listed below.