I am trying to find a totally free screen capture application for Windows and MacOS. Is there any free apps that don't put watermark on the video ?
Open Broadcaster Software is a (good)
Free and open source software for video recording and live streaming. Download and start streaming quickly and easily on Windows, Mac or Linux.
Agree with Gyan that Open Broadcaster Software is probably the best free tool.
Or if you have an ATI videocard you probably have Radeon Software installed which can Record & Stream. Ofcourse you don't have to stream.
Also VLC can do it. It's tucked away beneath: Media tab -> Convert / Save option -> Capture Device.
I'm often using Calipio to record my screen, which is free for up to 20mins of recordings.