What the editor can do
Text with size, color and bold; white-out; highlighter; boxes; images such as signatures and stamps. Any object can be moved or deleted.
Removing hidden content
With “Remove whited-out content” enabled and a white-out box present, the entire PDF is rebuilt from images of every page. Original text layers, resources, forms, links, bookmarks, attachments and document properties are not copied. Original text on all pages is no longer selectable; file size may increase. New editor text, images and white-out are also flattened in their on-screen stacking order. Visible data on other pages remains: check it before sharing. With this mode disabled, white-out only covers content visually and does not remove it from the file.
Where is the file processed?
Right in your browser. The document is not uploaded to MediaTut servers — you can verify this in the Network tab of developer tools.