SnapRect

SnapRect is a simple but powerful screen capture tool. Unlike most other screen capture tools SnapRect can capture a specified rectangle area over and over again. SnapRect comes with dimension presets and can also constrain dimensions of captured rectangles. Snaprect has a timer as well as a timelapse function. Images are captured to the clipboard but can also be saved in different file formats.

Best of all it's FREE!!! Just download from links below, unpack and run!

Download MacOS version (64 bit)
Download Windows version (Win 7/10)

Above a picture of SnapRect in collapsed mode. Set the coordinates of the rectangle to snap or click the "Set Rect" button to open and position the SnapRect window. Click the "SnapRect" button to capture the image behind the rectangle to the clipboard. See picture below.

Click the little arrow in the lower right corner to expand Snaprect for additional options.

Select preset dimensions to capture images of specified sizes.

Constrain dimensions of the capture rectangle.