PDF metadata is information stored inside a PDF that describes the file rather than appearing on its pages, such as its title, author, the software that made it, and when it was created and last changed. Most of it is written automatically. It lives in two places in the file, and it travels with the PDF wherever the file is sent.
The two places PDF metadata lives
A PDF can hold its details in two separate stores. Many files use both, which is why one tool can show details that another misses.
The document information dictionary
This is the original home of PDF metadata, part of the format since its first version. It is a short list of named fields, which viewers show in their Document properties panel:
| Field | Meaning |
|---|---|
| Title | The document’s title |
| Author | The person or account that made it |
| Subject | A short description |
| Keywords | Words to help find it |
| Creator | The program the original content was made in |
| Producer | The program that wrote the PDF |
| CreationDate | When the PDF was first made |
| ModDate | When the PDF was last changed |
XMP
XMP (Extensible Metadata Platform) is a newer format, created by Adobe and now an international standard (ISO 16684-1). PDFs have been able to include it since PDF 1.4. It stores details as a block of XML inside the file, and can hold far more than the classic fields: editing history, rights information, and custom fields added by publishing software.
In the current version of the format, PDF 2.0, the document information dictionary is deprecated in favour of XMP, apart from the two dates. Archival PDFs (PDF/A) must include XMP. In practice, most PDFs you receive still use the older dictionary, often alongside XMP.
Where else details hide
The two stores above are what most people mean by metadata. A PDF can also carry details that viewers don’t show in their properties panel:
- Comments and annotations, each with the reviewer’s name and the time it was made.
- Attachments, which are whole files embedded inside the PDF.
- Image data, such as the camera model, the date a photo was taken and its GPS location.
- Earlier versions, left behind when changes are added to the end of the file instead of rewriting it.
Hidden data in PDFs goes through each of these, and how to check for them.
Why PDF metadata matters
Privacy
Metadata often includes names, the company a computer is registered to, and the software and operating system used. Photos inside a PDF can reveal where they were taken. None of this is visible on the page, so it is easy to share without realising.
Provenance
Dates, software names and saved versions give clues about where a file came from and whether it was changed after it was made. They can be edited, so they suggest rather than prove. See Can you tell if a PDF has been edited?
Organisation and search
Document management systems, library catalogues and some search tools read the title, author and keywords to file and find documents. A PDF with a clear title is easier to find than one called “Document1”.
How to see a PDF’s metadata
Open the file’s document properties: in Chrome, from the viewer’s three-dot menu; in Adobe Acrobat Reader, with Ctrl+D (Cmd+D on a Mac). For everything, including the XMP copy and saved versions, use Verify Metadata, which reads the file in your browser without uploading it. The step-by-step guide is How to check a PDF’s metadata.
How to change or remove it
- To change the title, author, subject or keywords, use Metadata Editor.
- To strip details out, use Metadata Remover, which writes a fresh file so earlier versions don’t survive.
The guide How to remove metadata from a PDF compares the main methods.
Frequently asked questions
Is PDF metadata visible when someone opens the file?
Not on the page. Anyone can see it, though, by opening the file’s document properties in their viewer, and dedicated tools show the rest.
Does every PDF have metadata?
Almost every PDF has some, because the software that makes it usually records at least its own name and the dates. Some files have very little, especially ones that have already been cleaned.
What is the difference between Creator and Producer?
Creator is the program the content was written in, such as a word processor. Producer is the program that turned it into a PDF. They are the same when a program exports its own PDFs, and different when another tool did the conversion.
What is XMP metadata in a PDF?
XMP is a standard way of storing metadata as XML inside a file. In a PDF it sits alongside, or instead of, the older list of document details, and it can hold more information, such as editing history.
