Questions

The ones that actually get asked

How much smaller will the file get?: It depends on what is inside. A document full of scans drops noticeably; a text-only file barely moves, because there is nothing there to compress.
Will the text go blurry?: Text stays text. Compression touches images, so the difference shows in scans and photographs.
Does the file leave my device?: Yes. This is a server tool, unlike merging and splitting, which run in your browser.
How long do I have to download it?: Sixty minutes, then the result is deleted and the processing has to be run again.
What is the limit?: 100 MB per file and 50 files in one task.
Does it work on a scanned document?: It does, and that is usually where it helps most. It will not turn the scan into searchable text, though — that is a different thing this tool does not do.
Do I pay from the start?: No. Running the tool needs no account; paying is about the download: 7 days at an intro price, then monthly.