voidtools forum

Could someone recommend an efficient method or tool for compressing JPEG images while maintaining their quality? I've tried online jpeg compressor, which offer instant deletion after compression. Now, I'm looking a similar feature in an offline, open-source compression tool. Any suggestions for MAC?

You'll need to clarify what you intend by "maintaining their quality"
If you mean EXACTLY the same then they'll be best left as they are.
If you don't mind loss to the picture that's not noticed by humans then it will depend 1. how quickly you want to compress them all, 2. how quickly you want them to reopen, 3. whether you want other people to be able to open them without installing anything.
There are plenty of compressors better than the standard jpg, but they are often very slow to do the save (so could take forever to convert a lot of files), and also slower than jpg to open (unless an optimised jpg that was only slow to save). JPG2000 would be a case in point.
Generally XNView covers MACs - https://www.xnview.com/en/apps/
If you have a lot, it may also be easier to get a larger drive or just downsize most the images in size and/or quality as a JPG (JPG is fast), unless doing something technical a lot of images don't need to be as large and high quality as they are.
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This link may also help -
https://tsev.dev/posts/2023-11-10-shoul ... ge-format/
My general impression is that when quality settings are high (to create faithful copies) there's not a huge amount to gain, but when quality settings are low there is more. I did a while back play around with some formats like webp and found there was negligible benefit for the quality level I use, but a huge problem with speed (jpg is fast), and a quick test of avif suggests a similar situation.