RealVNC 6.1 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available.
Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. The software lies within System Tools, more precisely Remote Computing. The actual developer of this software for Mac is RealVNC Limited.
From the developer:
RealVNC provides remote control software which lets you see and interact with desktop applications across any network.
The software has a widespread user base from individuals to the largest multi-national companies. Founded by the original developers of VNC to promote, enhance and commercialize VNC.
You may want to check out more Mac applications, such as VNC Viewer Pro, which might be similar to RealVNC.