How to check metadata with ExifTool
Use ExifTool as a local checking tool for high-risk files, then read the results, remove what is needed, and recheck.
Before publishing a file anonymously, you need to check what remains inside the file.
Images, PDFs, Office documents, audio, and videos may contain metadata that is not visible on the screen.
ExifTool is a widely used tool for checking that metadata locally.
Because you can inspect files without uploading them to a browser-based checking site, it is an important option before anonymous publication, source protection, or whistleblowing.
However, using ExifTool does not automatically make the file safe.
You need to read the displayed information, judge what is risky, and recheck after removal.
What is ExifTool?
ExifTool is a tool that can read and write metadata in many file formats.
It is used not only for image EXIF, but also for checking metadata in a wide range of formats, including PDFs, Office documents, audio, and videos.
On the official site, you can check supported formats, tag lists, usage, and update information.
URL : https://exiftool.org/
The reason for introducing ExifTool in the context of anonymity is that it can be used locally.
If you upload a file to an external web service for checking, the file content, source IP address, time, and browser information are handed to that web service.
For high-risk files, checking locally first is safer.
What can you check?
The information ExifTool can check changes depending on the file format.
| Format | Information to check | Anonymity caution |
|---|---|---|
| Image | GPS, date and time taken, model name, editing software | Shooting location and routine places become visible |
| Creator, creation app, update time | Document source and work environment become visible | |
| Office | Author, company name, information related to edit history | Can reveal clues about affiliation and the creation environment |
| Audio | ID3 tags, creation date and time, app name | Recording environment and creator information remain |
| Video | Creation app, date and time recorded, location information | Combines with video content |
ExifTool is a tool for looking at information inside a file.
It does not automatically judge the photo background, video audio, document text, or the communication path used to send the file.
Looking with ExifTool is not the end
When you run ExifTool and information is displayed, that is not the end.
Next, judge how that information relates to anonymity.
| Displayed information | Reason to look |
|---|---|
| GPS Latitude / GPS Longitude | Check whether shooting location remains |
| Create Date / Date Time Original | See whether capture or creation time connects to behavior |
| Make / Model | See whether the camera or smartphone model becomes a clue |
| Author / Creator | Check whether a creator name or account name remains |
| Software | See whether an editing app or work environment appears |
The names of displayed items change depending on the file format and creation app.
If an unfamiliar item appears, do not immediately treat it as safe.
Look at the item name, value, and file context, then judge whether it is information that can be published.
How to read displayed values
In ExifTool output, item names are often displayed in English.
You do not need to understand every item perfectly.
First, prioritize values that are likely to relate to anonymity.
| Priority | Items to look at | Reason |
|---|---|---|
| High | GPS, location, latitude and longitude | Directly shows a place |
| High | Author, Creator, Owner | Shows a creator or account name |
| High | Date, Create, Modify | Connects to activity time or work time |
| Medium | Make, Model, Software | Becomes a clue to the device or editing environment |
| Medium | File Name, Directory | Personal information may appear in filenames or storage locations |
When many unfamiliar items appear, it can feel worrying.
However, what you should look at first is place, name, time, device, and filename.
These are types of information that tend to directly affect anonymity.
Do not run a removal command first
ExifTool can also be used to remove metadata.
However, beginners should avoid immediately running a removal command.
First read what is inside and understand what should be removed.
| What to do first | Reason |
|---|---|
| Copy the original file | To avoid damaging the original |
| Look at output before removal | To understand what is risky |
| Create a publication copy | To separate the original from the public version |
| Recheck after removal | To judge whether removal succeeded |
| Check appearance too | To look at clues other than metadata |
Removal operations are convenient, but the fact that you removed something does not by itself let you judge safety.
Comparing before and after removal is important.
Basic checking procedure
The way to think when using ExifTool follows this order.
| Order | Task | Reason |
|---|---|---|
| 1 | Copy the original file | Do not mix the original and the publication copy |
| 2 | Check metadata on the copy | Understand what remains |
| 3 | Classify dangerous items | Separate GPS, creator, date and time, and app name |
| 4 | Perform removal or regeneration | Create a publication copy |
| 5 | Check again with ExifTool after removal | See whether processing succeeded |
| 6 | Check the appearance of images and document text | Look at clues other than metadata |
For high-risk files, compare the results before removal with the results after removal.
If you do not check what disappeared and what remained, you cannot judge whether removal succeeded.
With some formats such as PDFs, even if metadata appears to have been removed by ExifTool, the original metadata may remain inside the file. Check format-specific limitations, and if necessary use other procedures such as qpdf or regeneration before rechecking.
Why not upload to an external service?
Metadata checking sites are convenient.
However, for files where anonymity matters, uploading to an external site itself becomes a new risk.
| Checking method | Advantage | Caution |
|---|---|---|
| Local ExifTool | Can check without handing the file outside | The device itself still needs to be safe |
| Web checking service | Easy to use | File content, IP address, and time are handed to the service side |
| Checking after social media upload | Close to the actual publication state | It may already have been published or sent |
For highly confidential files, reporting materials, whistleblowing materials, and personal photos, it is important to decide not to hand them to an external site from the start.
Local checking is not a complete solution, but it matters because it avoids increasing unnecessary parties you must trust.
Limits of ExifTool
ExifTool is powerful, but it is not a tool that judges anonymity as a whole.
Even if metadata is gone, the following information remains.
- Photo backgrounds and reflections
- Voices and environmental sounds in video or audio
- Body text in PDFs and documents
- Filenames
- Sending time and upload destination logs
- Account and cloud sharing history
ExifTool is "a tool for looking at metadata inside a file."
To protect anonymity, check content, appearance, sending paths, and account operation separately too.
How to use it in high-risk situations
For whistleblowing, reporting materials, activity records, personal photos, and similar files, also think carefully about how you use ExifTool.
If you check on a workplace or school device, device usage logs, file access history, cloud sync, and antivirus software logs may remain.
Also, if you keep checking results as screenshots, those screenshots may show file paths or usernames.
In high-risk situations, judge not only the file itself but also where you open it, where you save it, and how you handle the checking results.
ExifTool is a powerful checking tool.
However, if the operation is poor, the checking work itself becomes a new trace.
Summary
ExifTool is a widely used tool for checking file metadata locally.
It can check creators, date and time taken, GPS, app names, and editing information left in images, PDFs, Office files, audio, videos, and similar files.
What matters for anonymity is not the act of using ExifTool itself.
It is reading the displayed information, judging what is risky, and rechecking after removal.
If you upload a file to an external site for checking, you hand the file and access information to that site.
For high-risk files, prioritize local checking, and finally also check backgrounds, reflections, document text, and sending paths beyond metadata.
Related tools
ExifTool
An external resource related to this article. Open it only when it fits your situation and threat model.
Why it is listed: It can help with the article topic, but it is outside Anonymity Sense and should be checked before use.
URL : https://exiftool.org/
MAT2
An external resource related to this article. Open it only when it fits your situation and threat model.
Why it is listed: It can help with the article topic, but it is outside Anonymity Sense and should be checked before use.