JStrip is a compact free tool which can reduce the size of most JPEG images, while preserving their image quality.
The program works by scanning the files, then removing all the data which isn't a part of the picture. And it's surprising how much this can be. Your files might contain comments, for instance; metadata; thumbnails, colour profiles and assorted other bits and pieces, none of which have anything to do with the image itself.
You shouldn't expect too much from this. Normally these extra chunks take up something under 100 bytes, so you could run jStrip on large files - your digital photos, say - and find it makes no difference at all to the disk space they use.
The program may still be worth using to optimize web graphics, though, and we did find occasional exceptions where it delivered spectacular results (a tiny web button dropped from 11,372 to 749 bytes, a 93.4% compression rate).
In use, the program is very straightforward. Clicking File > Options lets you choose what you'd like to remove, then you simply select the folder containing your images, click Start and check the results: easy.
Just keep in mind that jStrip will overwrite your original files with the stripped versions. The program doesn't appear to harm images so this shouldn't be a problem, but we'd recommend you work with copies anyway, just to be safe.