A PDF can carry far more than what’s on its pages: the names of the people who made and reviewed it, the software and computer used, earlier drafts saved inside the file, attached files, and the location where its photos were taken. Before you send a PDF that matters, check its details and remove what you don’t want to share. It takes a minute, and it’s free.
Eight kinds of hidden data, and where they come from
| Hidden data | Where it comes from | How to remove it |
|---|---|---|
| Author and company names | The account and licence of the computer that made the file | Metadata Remover, or untick document properties when exporting |
| Software and operating system | The programs that made and saved the PDF | Metadata Remover |
| Created and modified dates | Set automatically on every save | Metadata Remover |
| Comments and review notes | Annotations added during review, with names and times | Delete them, or tick comments in Metadata Remover |
| Attachments | Files embedded in the PDF | Metadata Remover |
| Photo details and GPS location | Data the camera or phone stored in each image | Metadata Remover |
| Earlier versions | Changes added to the end of the file instead of rewriting it | Any tool that writes a fresh copy |
| Text under black boxes | “Redaction” done by drawing shapes over text | A proper redaction tool (see below) |
Names, software and dates
The software that makes a PDF usually fills in its details automatically. The Author field often holds the name on the computer account, which may be your full name or your employer’s. The Creator and Producer fields name the programs used, sometimes with version numbers and the operating system. The dates record when the file was made and last saved, down to the second.
None of this appears on the page, but anyone can read it in their viewer’s document properties.
Comments and review notes
Comments, highlights and sticky notes are stored with the reviewer’s name and the time they were added. Collapsing or hiding them in a viewer doesn’t remove them. If a PDF went through a review, check for notes before sending it outside the team.
Attachments
PDFs can contain whole files, such as spreadsheets, images or earlier drafts, attached to the document or to a single page. They are easy to miss because many viewers only show them in a side panel.
Photos that know where they were taken
Photos from phones and cameras often store details about the picture: the device model, the date and time, and the GPS coordinates of where it was taken. When a photo goes into a PDF, some of that data can come along with it, for example in a scanned receipt or a photographed form. Images to PDF leaves location data out when it builds a PDF, and Metadata Remover strips it from PDFs that already have it.
Earlier versions inside the file
Many programs save a PDF by adding the changes to the end of the file and leaving the old version underneath. A file saved several times can hold several versions, and the earlier ones can include text, names or values that were later changed or deleted. Tools that rewrite the file from scratch, such as Metadata Remover, leave only the current version.
Black boxes that don’t hide anything
The most damaging kind of hidden data isn’t metadata at all. Drawing a black rectangle over text, or highlighting it in black, only covers the words. The text is still in the file and can be selected, copied or searched.
To hide text for good, use a real redaction tool, such as the Redact tool in Adobe Acrobat Pro, which deletes the text under the box. Then search the saved copy for the words you removed, to make sure they’re gone.
PDF Check’s tools don’t redact text on the page, so use a dedicated redaction tool for that step.
A checklist before you send a PDF
- Open the file in Verify Metadata and read the author, software and dates.
- Look for comments, attachments and more than one saved version.
- If anything shouldn’t travel with the file, make a clean copy with Metadata Remover.
- If you redacted anything, search the final copy for the hidden words.
- Check the clean copy once more before you send it.
Frequently asked questions
Can a PDF reveal my location?
It can, if it contains photos that stored GPS coordinates when they were taken. The PDF’s own details don’t usually record a location, but the images inside it might.
Does saving as PDF remove hidden data?
Not reliably. Converting to PDF usually drops some details from the original document, but adds new ones, such as the software name and dates, and can carry over comments and image data.
Can someone see what I deleted from a PDF?
Sometimes. If the file was saved by adding changes to the end, the earlier version, including the deleted content, can still be inside it. Text covered with a black box is often still there too. Writing a fresh copy removes earlier versions. Proper redaction removes covered text.
Is it safe to check a PDF online?
It is when the checker works in your browser and doesn’t upload the file. Verify Metadata and Metadata Remover both run on your device, so your PDF never leaves it.
