Fingerprint a PDF to trace leaks

Generate a separate copy of a PDF for each person on your list, with a faint code hidden in the corner of every page and the same code written into the file's metadata. If a copy ever leaks, matching its code against the manifest tells you which recipient it came from. Everything is generated in your browser, including the manifest.

Fingerprint PDF

faint per-copy code · in the page and the metadata

Ready

Loading tool…

How to Fingerprint PDF

Add your PDF. Drag the document you're about to send out onto the drop zone.
List your recipients. Type one name per line — colleagues, clients, whoever is getting a copy.
Generate copies. Each recipient gets their own PDF with a distinct hidden code, delivered together as one ZIP.
Keep the manifest. The ZIP includes a manifest.txt matching each code back to a name — save it somewhere private. It's the only copy.

What's actually hidden in each copy

Two things, deliberately redundant. A short code is drawn in the bottom corner of every page at 4pt and low opacity — small and faint enough to go unnoticed at normal reading size, but it survives printing and screenshots because it's part of the page content, not a file property that a screenshot would strip away.

The same code is also written into the PDF's Keywords field, which doesn't show up when the document is opened but can be checked in any reader's document properties. If a leaked copy has been re-saved or flattened in a way that touches the visible page, the metadata layer is a second chance to identify it.

What this is and is not

This is a deterrent and a traceability tool, not a lock. Anyone who receives a fingerprinted PDF can still read it, print it, forward it — that's the point, the document has to remain usable. What changes is that if it turns up somewhere it shouldn't, there's a way to find out whose copy it started as.

It's also not forensic-proof. A corner mark that small can be cropped out by someone who knows to look for it, and the metadata field can be stripped with a tool like this site's own Privacy Scanner. Against casual leaks — a document forwarded further than intended, a screenshot shared without thinking — it works well. Against someone deliberately trying to defeat it, treat it as a speed bump, not a wall.

For content that needs a stronger guarantee, pair this with Encrypt PDF so a copy also requires a password to open at all.

Frequently asked questions

Can the hidden code be seen just by opening the PDF?

The corner mark is faint but technically visible if you know to look for it in the bottom corner. The metadata code is invisible unless someone checks the document's properties.

What happens if I lose the manifest?

There is no way to recover it — nothing about the fingerprinting is stored anywhere except in the ZIP you downloaded. Save the manifest somewhere you won't lose it, ideally not the same place as the fingerprinted copies themselves.

Can someone remove the fingerprint?

A technically capable person could crop the corner mark and strip the metadata. This tool is built to catch accidental or casual leaks, not to resist a determined, technical adversary.

Are my files or recipient names uploaded anywhere?

No. Every copy, and the manifest matching them to names, is generated entirely in your browser.

Does the fingerprint change how the document looks or behaves?

Only by a nearly invisible mark in one corner of each page. Everything else about the document — its content, its layout, its file size — is unchanged.

How many copies can I generate at once?

One per line in the recipient list, with no fixed limit. Very long lists simply take longer to process.