KolourPaint is one of the common picks for the question “What do I use for basic image editing tasks now that I own my PC instead of leasing it and no longer have MS Paint”, being simple and lightweight, which is handy when you’re opening dozens of images to make quick crops and don’t want to add a single purpose program for just cropping (and everyday cropping/circling/etc. of images). One nifty thing I’ve found in it that I’m not aware of in other lightweight editors (though I’m hardly an expert on them) is the “set as image (crop)” (ctrl+t) function that reduces the image to only what is currently select and “autocrop” (ctrl+u) that tries to remove solid color blocks around the image/selection. With these and save as (ctrl+shift+s) I’ve managed to get basic cropping tasks down to just a few seconds. Other basic editors may have similar functions (GIMP, Affinity, and Photoshop all have it as crop to image), and there’s likely better ways to do this, but I’m sure people will share those in the comments, and I’ve found it works for me so I’m sharing it.