Select sensitive areas and remove their pixels before creating a new image-only PDF. Original text layers and attachments are not copied.
Use the synthetic practice document to cover the invented reference number on page one. Add a region large enough to include every digit. Process the image-only copy, then open the downloaded PDF in another reader and inspect the covered area, the other pages and any surrounding information.
All pages become images. Searchable source text, forms, bookmarks, links, attachments and digital signatures are not carried over. Region completeness still depends on your review.
Drop one PDF here, or use Open PDF. Maximum 50 MB.