The data a PDF carries that the page does not show
Most PDFs carry more than their pages. The program that wrote the file usually adds the author's name, the software and sometimes the computer it ran on, and when the document was created and last changed. Many add a hidden XMP copy of all that with an editing history. Photos placed in the document can carry the date, the phone and the place they were taken. None of it shows on the page, and all of it travels with the file.
Updated
Which tool you need
Sending a document outside your organization
Remove PDF Metadata with every hidden-data option on: the author, software and dates go, and so does the XMP history.
The title shows wrongly in a browser tab or a search result
Remove PDF Metadata lets you edit the title, author, subject and keywords rather than clear them.
A PDF made from phone photos
Keep Remove camera details from photos on: the date, device and location stored in each JPEG go.
You want to see the metadata without changing anything
PDF to JSON exports the properties and the raw XMP for you to read.
What stays
Words on the pages are content, not metadata: a name in a footer, the text of a comment or a form value stays, though who wrote a comment and when is removed. Use Flatten PDF to lock comments and fields in place, or edit the document itself.
The file still says it was written by PDFCheetah, as every PDFCheetah download does.
Earlier versions saved inside the file
Many programs save a change by adding it to the end of the file, so the earlier version stays inside, and text you deleted can still be recovered from it. With Remove leftover and app-private data on, every part of the file the finished document no longer uses is removed, and so are page thumbnails, which can show a page as it looked before an edit.
The same option gives the copy a new file identifier. Most PDFs carry one from their first save, and keeping it would let the cleaned copy be matched with the original.
What the cleaned copy says about itself
Before anything is removed, the tool lists what the file says beyond its four editable properties: the program that created it, the PDF producer, the dates and any custom entries a program added.
Afterwards the document properties hold only the title, author, subject and keywords you kept, with PDFCheetah as the program, and no dates. Form fields keep their names, because a form needs them to work.
What to know before you start
- Camera details are removed from JPEG photos; other picture formats are left as they are.
- Text on the pages is not metadata and is not changed.
- A locked PDF has to be unlocked first.
- Files attached inside the PDF, and any scripts, go along with the metadata.