Glossary · Glossary · Document security
Document metadata: definition, risks and how to clean it
Anonimatum Team
In short
Metadata is the data a file keeps about itself: who created it, when, with which software, how it was edited and, for photos, even where it was taken. It does not appear on the page, but it travels with the file.
When you email a Word report, publish a PDF on your website or attach a photo to a case file, you share more than what is on screen. The file carries technical and contextual information that anyone can read in its properties or with free tools.
Much of it is personal data: the name of the person who drafted the document, whoever reviewed it, their comments or the GPS coordinates of their home. Before publishing or disclosing a document, cleaning its metadata matters as much as redacting the visible content properly.
What metadata each file type holds
| Format | Typical metadata and hidden content |
|---|---|
| Word, Excel, PowerPoint | Author, last saved by, company, created and modified dates, template, revision number, comments, tracked changes, hidden text, hidden rows or sheets, speaker notes, thumbnail |
| Document information dictionary (author, title, subject, creator application), XMP metadata, annotations, attached files and sometimes earlier versions kept by incremental saves | |
| JPEG photos and similar | EXIF: camera or phone make and model, exact date and time, settings, sometimes a serial number and GPS coordinates; also IPTC and XMP blocks |
Strictly speaking, properties (author, dates, software) are metadata, while comments, revisions and hidden content are part of the document itself, just not visible at first glance. The ICO's checklist on hidden personal information covers both, and both can contain personal data.
Privacy risks
- Identifying authors and reviewers: the author or “last saved by” field can reveal who wrote a report that was meant to be anonymous, such as a witness statement or a whistleblowing report.
- Comments and tracked changes: deleted sentences, replaced names or internal opinions that are still in the file.
- Location: a phone photo may carry the GPS coordinates of where it was taken, sometimes someone's home.
- Undermining a redaction: a correctly redacted PDF whose title or subject property still contains the name you meant to hide.
- Context for attackers: folder paths, server names or software versions.
Under the UK GDPR and the EU GDPR, personal data is any information relating to an identified or identifiable living individual (Article 4(1)). A user name in a PDF's properties is personal data just like a name in the body text, and disclosing it without need breaches the data minimisation principle.
How to remove metadata
- In Microsoft Office, run the Document Inspector before sharing, and accept or delete tracked changes and comments in the source file.
- In PDFs, remove document properties and XMP, annotations and attachments. Converting to PDF is not enough, because Word properties can carry over.
- In photos, strip EXIF or export without metadata, and check that the location is gone.
- Verify the output by opening the file properties rather than trusting that the tool worked.
Removing metadata does not redact anything visible on the page. If names or account numbers appear in the body, you also need true document redaction.
Good practice before publishing
Build the clean-up into your workflow instead of relying on memory: decide who checks, at which point (just before signing off or publishing) and how it is verified. Work on a copy, keep the original on file and release only the cleaned version. If documents come from templates, fill in properties with generic values, such as the team name rather than a person's. Our article on hidden metadata in Word and PDF files walks through common cases.
What Anonimatum does with metadata
Anonimatum has a dedicated screen to remove metadata from PDFs and other files. It accepts PDF, modern Office documents (.docx, .xlsx, .pptx) and JPG, PNG and WebP images. For PDFs it removes document properties (author, title, dates…) and XMP metadata; for Office files, package properties and typical metadata parts, including embedded thumbnails; for images, EXIF and auxiliary chunks, while keeping the colour profile. You can process several files at once and download them as a ZIP.
Frequently asked questions
Is metadata personal data?
It can be. An author name, the user who last saved a file or a photo's GPS coordinates relate to identifiable people and fall under data protection law.
Does saving a Word file as PDF remove its metadata?
Not entirely. Some Word properties are usually copied into the PDF, which adds its own. Clean the PDF afterwards.
Does removing metadata replace redaction?
No. They are complementary: one cleans hidden file information, the other removes visible data from the content.
How can I see a file's metadata?
On Windows, under Properties > Details; in a PDF reader, under Document Properties; in Office, under File > Info.
Share files without hidden extras
See the plans and start removing metadata and redacting personal data from your PDFs, Office files and images.