You can use ShortPixel Image Optimizer and NitroPack simultaneously, but you have to disable ShortPixel's WebP conversion. Our service converts images to WebP by default, so ShortPixel's WebP conversion must be disabled to avoid compatibility issues.

Here's how you can quickly do that:

1. In your WordPress admin panel, go to Plugins, find ShortPixel Image Optimizer, and click on Settings.

2. Go to Advanced, find the "WebP Images" setting, and disable it.

3. Save any changes, and purge your NitroPack cache.

However, ShortPixel Adaptive Images (which is a different plugin from ShortPixel Image Optimizer) and NitroPack are not compatible. The whole ShortPixel Adaptive Images plugin has to be disabled when working with NitroPack.