Document leak checker
Before you send a file to someone, this shows what travels along with it without being visible. It only looks — it does not change your file.
0 B uploaded — this page has not sent your file anywhere?
Other checking sites upload the file, inspect it on their servers and say it is deleted after a while. Until then the file sits on someone else's machine. Here there is no upload step at all. See how to verify it yourself →
What it looks for
Text still alive under a black box
A black rectangle drawn on top hides nothing: copy the page and the text comes straight back. When that happens, the actual text is shown to you.
Deleted sentences and comments
Tracked changes still carrying what was deleted, comments, hidden sheets, hidden rows and columns, and the whole source table embedded behind a chart.
Names left in the file
Author, last person to save it, company, and the original file name from before it was renamed.
Traces left in photos
Where it was taken (GPS), camera serial number, capture time — and bytes appended after the end of the image, where the uncropped original sometimes survives.
How to use it
- 1Choose the file you are about to send. It never leaves your browser.
- 2Read each finding and decide for yourself whether it may go out.
- 3If something must be covered, remove it in Redact / Black Out.
See what travels along with a file before you send it
Text you deleted or covered on screen is often still inside the file. This tool opens a PDF, Word, Excel, PowerPoint, JPG or PNG file and shows you, word for word, what the recipient could pull out of it even though you cannot see it. It only inspects and never changes the file, and the file never leaves your browser.
A closer look
For a PDF, each page is actually drawn, and wherever a character should be but there is no contrast at all, that spot is matched against the text stored in the file. Live text found under an opaque rectangle is reported as “Covered up, but the text is still there”, and invisible text with no shape over it, such as white-on-white, as “There is text you cannot see”; either way the actual words are shown. The check also covers document fields such as author and title, the file’s original name from before it was renamed, embedded attachments, scripts, values left in form fields, notes and comments, and areas hidden by cropping. The covered-text and comment checks run on the first 30 pages; for longer files the result says plainly that the rest were not examined.
In Word, Excel and PowerPoint files it looks for deleted sentences still stored as tracked changes, hidden text, comments, hidden sheets, rows and columns, hidden slides, the complete source table stored behind a chart, and properties such as author, last saved by and company. In photos it looks for GPS coordinates, camera model and serial numbers, capture time, and bytes appended after the image ends, where an uncropped original sometimes survives. Findings are grouped as “leaking as is”, “still in the file” and “worth knowing”, and every result carries a reminder that finding nothing does not mean the file is safe.
How to use it
- Drag in the one file you are about to send, or press Choose file. For a PDF, progress such as “Looking at page 3 of 30…” is shown.
- Read the results from the top. Each finding shows the page and the exact strings still in the file; when there are more than eight, the rest are summarized as “N more”.
- Decide for each item whether it may go out. Mostly harmless details, such as the program that produced the file or its dates, are grouped under “worth knowing”.
- If something must go, press Go to Redact / Black Out below the results. For a Word or Excel original, fix it in that program and then check it again.
When it helps
Common snags
Tip Check the file once more after fixing it. Even after you accept all tracked changes and delete comments in Word, the author and company in the document properties often remain.
Questions
If it finds nothing, is my file safe?
No. This tool can only say "here is what I found". Some formats cannot be checked, and some ways of hiding things cannot be detected at all. The result screen says so as well. For anything important, check it yourself too.
How can it tell that text under a black box is still there?
The page is drawn as it would look on screen. Where a character should be but there is no contrast at all — nothing a human eye could read — it is matched against the text stored in the file. If the text is still there, you are shown exactly what it says.
Does it work on scanned documents?
A scan has no text layer, so covered text cannot be found in it. The result says that plainly instead of quietly passing the file. Document properties and cropped-away areas are still checked.
Can I remove what it finds here?
No. This tool only inspects. Removing is done by Redact / Black Out, which really deletes the content instead of drawing a black rectangle over it.
Is my file uploaded?
No. Opening the file and inspecting it both happen inside the browser. It works with your connection switched off.