Kap is an open source screen recording tool for macOS/OS X 10.10+ by Wulkano
Once installed and running Kap sits in your menubar.
Selecting Kap in your menubar brings up the following
From here you can select the aspect ratio which have a few preselected sizes but you can also manually set the screen size. Once you have your aspect ratio set click on the record button and an overlay appears showing which area that will be recorded if you want you can now resize the overlay. Click the record button again and your screen recording will start, simple.
I personally find this a great minimalist option for screen recording. I don't use screen recording much but this is better than the few others I have used.
Download and install from their website
If you are interested you can view the source code here
