I use SnagIt from TechSmith for screen capture and then mark and label them to post ideas on Twitter and my website. SnagIt is an excellent product. I have no commercial association with them, just a regular user of their product. I am happy with SnagIt.
However, SnagIt is not free.
TechSmith Capture (earlier called Jing) is a free screen capture product from the same company TechSmith. If you do not need all the features of SnagIt, you may try out TechSmith Capture (Jing) to see if that meets your needs.
Here is the download link as of the 4th of July, 2022.
https://www.techsmith.com/jing-tool.html