OBS Studio - Free and open source software for video recording and live streaming for Mac, Windows and Linux.
placeholder.pics - Lightest way to include placeholder images in your design
Snagit - Screen Capture Software for Windows and Mac
PlaceKitten - Dead-easy placeholder images. Of kittens.
ShareX - ShareX is a free and open source program that lets you capture or record any area of your screen...
Fill Murray - Custom-sized placeholder images of Bill Murray