The Hidden Information in Every File
Every digital file carries more than its visible content. A photo does not just contain pixels -- it records where you were standing when you took it, what camera you used, and the exact date and time. A Word document does not just contain text -- it records who created it, who edited it, how many revisions were made, and sometimes the names of people who commented on it. A PDF may contain the software that generated it, the original author's name, and hidden text from earlier drafts.
This invisible information is called metadata -- data about data. It serves useful purposes: organizing files, enabling search, maintaining version history, and proving authenticity. But it also creates privacy and security risks that most people never consider.
When you share a photo online, the GPS coordinates in its metadata can reveal your home address. When you send a legal document, the revision history in its metadata can expose deleted text. When you distribute a PDF, the author metadata can identify someone who wanted to remain anonymous.
This guide explains what metadata is, what information different file types contain, how to view it, and most importantly, how to remove it when privacy matters.
Types of File Metadata
Metadata falls into several categories depending on how it is created and stored:
Descriptive Metadata
Information that describes the content: title, author, subject, keywords, description. This metadata is typically set manually by the creator or by the application used to create the file.
Technical Metadata
Information about how the file was created: camera model, lens, exposure settings, software version, resolution, encoding parameters. This is set automatically by the hardware or software.
Administrative Metadata
Information about the file's lifecycle: creation date, modification date, access permissions, copyright, license information. Set by the operating system and applications.
Structural Metadata
Information about how the file is organized internally: page count, chapter structure, table of contents, embedded resources. Relevant primarily for documents and ebooks.
Metadata by File Type
Different file types carry different metadata, and the privacy implications vary accordingly.
Photo Metadata (EXIF, IPTC, XMP)
Digital photos carry the richest metadata of any common file type. The EXIF (Exchangeable Image File Format) standard stores:
| Metadata Field | Example Value | Privacy Risk |
|---|---|---|
| GPS coordinates | 37.7749, -122.4194 | High -- reveals exact location |
| Date/time taken | 2026-02-15 14:32:07 | Medium -- reveals when you were at a location |
| Camera make/model | Apple iPhone 16 Pro | Low -- identifies your device |
| Lens information | iPhone 16 Pro back camera 6.86mm f/1.78 | Low |
| Exposure settings | 1/120s, f/1.78, ISO 64 | Negligible |
| Thumbnail image | Embedded preview | Medium -- may show pre-crop version |
| Software | Adobe Photoshop 26.3 | Low -- reveals editing tools used |
| Serial number | Camera body serial number | Medium -- can identify the specific camera |
| Owner name | John Smith | High -- directly identifies the photographer |
The GPS risk is the most significant. A photo taken at home, when shared publicly, can pinpoint your address. Photos of children taken at school or at home are especially sensitive. Most social media platforms strip EXIF data from uploaded photos, but not all platforms do, and files shared directly (email, messaging apps, cloud links) typically retain all metadata.
IPTC and XMP metadata are additional standards used primarily by professional photographers and media organizations. They store copyright information, captions, keywords, contact details, and usage rights.
Document Metadata (DOCX, PDF, XLSX)
Office documents contain metadata that can expose sensitive information:
| Metadata Field | Found In | Privacy Risk |
|---|---|---|
| Author name | DOCX, PDF, XLSX, PPTX | High -- identifies the creator |
| Organization | DOCX, XLSX, PPTX | Medium -- reveals employer |
| Revision count | DOCX | Low -- shows editing history |
| Total editing time | DOCX | Low -- shows time spent editing |
| Comments and annotations | DOCX, PDF, XLSX | High -- may contain sensitive feedback |
| Track changes / hidden text | DOCX | Very high -- may expose deleted content |
| Embedded file paths | DOCX, XLSX | Medium -- reveals directory structure |
| Producer software | Low -- identifies generation tool | |
| Last saved by | DOCX, XLSX | High -- identifies last editor |
The "Track Changes" risk is particularly serious. A document with accepted track changes may still contain the full revision history, including deleted text, in the file's XML. Legal firms, government agencies, and journalists have all been exposed by metadata in DOCX files that was not properly removed before publication.
Video Metadata
Video files carry metadata similar to photos, plus additional fields:
- GPS coordinates (from smartphones)
- Camera/phone model
- Date and time of recording
- Duration, resolution, frame rate
- Audio codec and bitrate
- Software used for editing
- Chapter markers (in MP4 and MKV)
Audio Metadata (ID3, Vorbis Comments)
Audio files carry metadata through tag systems:
- ID3 tags (MP3): Title, artist, album, year, genre, track number, album art, lyrics
- Vorbis comments (OGG, FLAC): Similar fields in a different format
- iTunes metadata (M4A/AAC): Apple-specific fields including purchase email
Pro Tip: If you buy music from iTunes and share the M4A files, the files may contain your Apple ID email address in the metadata. Always check audio metadata before sharing purchased files. The same applies to audiobooks purchased from Audible or other platforms.
How to View Metadata
On Windows
File Explorer: Right-click a file > Properties > Details tab. Shows basic metadata for most file types.
For photos (EXIF): Open in the Windows Photos app, click the info icon (i), and scroll through the details.
Command line (ExifTool):
exiftool photo.jpg
exiftool -GPS* photo.jpg # Show only GPS data
exiftool -a -u -g1 document.pdf # Show all metadata, grouped
On macOS
Finder: Select a file, press Cmd+I (Get Info). Shows basic metadata.
Preview (for images): Open in Preview > Tools > Show Inspector > EXIF tab.
Terminal (mdls):
mdls photo.jpg # Shows Spotlight metadata
mdls document.pdf # Works for any file type
Terminal (ExifTool):
brew install exiftool
exiftool photo.jpg
On Linux
# ExifTool (most comprehensive)
exiftool file.jpg
# For images
identify -verbose image.png # ImageMagick
# For PDFs
pdfinfo document.pdf # Poppler utilities
# For audio
ffprobe audio.mp3 # FFmpeg
Online Tools
Upload files to our image converter or document converter to see metadata information during the conversion process. Some online EXIF viewers also display metadata without requiring software installation, but be cautious about uploading sensitive files to unknown services -- see our security and privacy guide.
How to Remove Metadata
From Photos
ExifTool (all platforms, recommended):
# Remove all metadata
exiftool -all= photo.jpg
# Remove only GPS data (keep other metadata)
exiftool -GPS*= photo.jpg
# Remove metadata from all JPGs in a directory
exiftool -all= *.jpg
# Remove metadata but keep orientation
exiftool -all= -tagsfromfile @ -Orientation photo.jpg
On Windows (built-in):
- Right-click the photo > Properties > Details
- Click "Remove Properties and Personal Information"
- Choose to remove all or select specific fields
On macOS (Preview):
- Open in Preview
- Tools > Show Inspector
- GPS data can be viewed but not easily removed via GUI -- use ExifTool instead
During conversion: Our image converter can strip EXIF data during format conversion. Converting HEIC to JPEG through our tool removes metadata by default.
From Documents (DOCX)
Microsoft Word:
- File > Info > Check for Issues > Inspect Document
- The Document Inspector shows all metadata categories
- Click "Remove All" for each category you want to clean
- Save the file
LibreOffice:
- File > Properties > clear all fields
- Tools > Options > Security > check "Remove personal information on saving"
Command line:
# Using ExifTool
exiftool -all= document.docx
# Using docx2txt to check what is in the document
python -c "import zipfile; z=zipfile.ZipFile('doc.docx'); print(z.read('docProps/core.xml').decode())"
From PDFs
ExifTool:
exiftool -all= document.pdf
Using qpdf:
qpdf --linearize --replace-input document.pdf
Using our tools: The document converter and compress-pdf tool can produce clean PDFs with minimal metadata. Converting a document to PDF through our service strips most application-specific metadata.
For more on securing PDF files, see our guide on how to password protect PDFs and our data privacy in file conversion guide.
From Videos
FFmpeg:
# Remove all metadata
ffmpeg -i input.mp4 -map_metadata -1 -c copy output.mp4
# Remove specific metadata
ffmpeg -i input.mp4 -metadata title="" -metadata comment="" -c copy output.mp4
HandBrake: By default, HandBrake does not copy metadata from the source file to the output, effectively stripping it during conversion.
From Audio Files
FFmpeg:
# Remove all metadata tags
ffmpeg -i input.mp3 -map_metadata -1 -c copy output.mp3
Specialized tag editors:
- Mp3tag (Windows): Bulk edit and remove ID3 tags
- Kid3 (cross-platform): Edit tags in MP3, FLAC, OGG, M4A
- Picard (cross-platform): MusicBrainz tagger with metadata editing
Pro Tip: When removing metadata from photos before sharing online, also check for embedded thumbnail images. Some photo editors create a thumbnail at the time of capture, then the user crops the photo. The full, uncropped image may still exist as the embedded thumbnail. ExifTool's -all= flag removes thumbnails, but simpler tools may not. Use exiftool -ThumbnailImage photo.jpg to check for embedded thumbnails.
Metadata and File Conversion
File conversion itself can add, remove, or preserve metadata depending on the tool:
| Conversion | Metadata Behavior | Notes |
|---|---|---|
| HEIC to JPEG | Varies -- some tools preserve EXIF, others strip it | Our converter strips metadata by default |
| DOCX to PDF | Author and title typically transfer; revision history stripped | Check the resulting PDF's properties |
| PNG to JPEG | PNG text chunks removed; JPEG EXIF added minimally | Different metadata systems |
| MOV to MP4 | Varies by tool; FFmpeg preserves by default | Use -map_metadata -1 to strip |
| WAV to MP3 | WAV metadata rarely carries over; new ID3 tags may be added | Audio content preserved, metadata reset |
| PDF to DOCX | Original PDF metadata may transfer to DOCX properties | Check and clean after conversion |
For file conversion workflows that prioritize privacy, see our data privacy in file conversion guide and the file conversion security guide.
When to Keep Metadata
Not all metadata removal is desirable. Metadata serves important functions:
Photography: EXIF data helps photographers organize and find photos by date, location, and camera settings. Removing it makes library management harder.
Publishing: Author, title, and copyright metadata in documents and ebooks is essential for proper attribution and discoverability.
Accessibility: PDF metadata (title, language, document structure) is required for screen reader accessibility. Removing it makes documents inaccessible to users with disabilities.
Forensics: Metadata can prove when a document was created, who created it, and whether it has been tampered with. This is valuable in legal and investigative contexts.
Music libraries: ID3 tags in audio files drive the display in music players. Without tags, your library becomes an unorganized collection of unnamed files.
The right approach is selective: remove metadata that poses privacy risks, keep metadata that serves useful purposes.
Best Practices for Metadata Hygiene
-
Check before sharing. Use ExifTool or the built-in file properties to review metadata before sharing files publicly or with untrusted parties.
-
Disable GPS in camera apps. On your phone, disable location tagging in the camera settings if you do not need it. This prevents GPS coordinates from being embedded in the first place.
-
Use Document Inspector. Before sending Word or Excel documents externally, always run the Document Inspector (File > Info > Inspect Document) and remove personal information.
-
Convert to strip. File conversion often removes metadata as a side effect. Converting a DOCX to PDF strips revision history. Converting a photo through our image converter removes EXIF data. Use this to your advantage.
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Separate originals from shared copies. Keep original files with full metadata in your private storage. Create metadata-stripped copies for sharing.
-
Batch clean before bulk sharing. If you are sharing a large number of photos or documents, use ExifTool's batch mode to clean all files at once rather than one by one.
-
Understand platform behavior. Social media platforms (Facebook, Instagram, Twitter/X) strip EXIF data from uploaded photos. Messaging apps vary: WhatsApp strips metadata, but Telegram's "send as file" option preserves it. Cloud storage (Google Drive, Dropbox) preserves all metadata.
Wrapping Up
File metadata is a double-edged sword: useful for organization and workflow, risky for privacy and security. The key is awareness. Once you know what metadata your files carry, you can make informed decisions about what to keep and what to remove.
For everyday sharing, the biggest wins come from removing GPS data from photos before posting, cleaning personal information from documents before sending externally, and being cautious about which tools you use for conversion. ExifTool is the most powerful single tool for metadata management across all file types, and it is free and open-source.
For conversion workflows that handle metadata responsibly, our image converter, video converter, and document converter provide clean, metadata-aware processing.
