Every other free compressor uploads your document to a server and asks you to trust a retention policy. This one has nothing to promise : the work happens on your machine, so there is no copy to keep.
The file is read straight from your disk into the page. Open your browser network tab and watch : no request is made.
We never receive the document, so there is no retention window, no deletion timer, and nothing of yours in a breach.
Turn off your wifi and compress anyway. The whole tool is a few hundred kilobytes of code running in your tab.