Does ShortPixel Website Optimizer re-optimize already optimized images?
ShortPixel Website Optimizer provides a simple web interface to our API, available for any PHP website, and can optimize images in any folder you give it.
You can add as many images as you want in the already optimized folders. If you click the "OPTIMIZE NOW" button again, your already optimized images will be skipped. No over-optimization! This is because ShortPixel puts a small file in the same folder where the images are.
Do not delete the .shortpixel file if you want to keep the data about previous optimizations.