Docs
How to take something out of a document so it is really gone, what a watermark can and cannot prove, and how to check any of it yourself. Written in plain English, for people who have bought nothing and may never need to. Every step is spelled out.
Removing what should not be there
Redacting a PDF so the words are really gone
A black box drawn over words in a PDF leaves the words underneath, where anyone can select and copy them. Here is why that happens, how to check a file you already have, and what actually removes them.
How to check whether a redaction actually worked
Four checks you can run on a finished document before you send it, each one catching a different mistake. No special software, and about two minutes in total.
Redacting a scan, where there is nothing to select
A scan is a photograph of a page, so covering something on it feels safe. Two things make it less safe than it looks — including a set of invisible words most people do not know their scanner added.
What a PDF says about you besides its words
Your name, the folders the file passed through, which software you used, when you edited it, and sometimes what the page said before you changed it. Removing the words removes none of it.
Why PDF passwords and no-copy settings are not protection
The no-copy and no-print settings are a polite request that any program is free to ignore, and one free tool strips them in a single step. The password that stops a file opening is a different thing, and that one is real.
Black boxes in Word and Google Docs survive the export
Drawing a black shape over words in a word processor and then saving as PDF carries both across. The shape is a drawing; the words are still words, sitting underneath it.
Marks, and what they prove
What a document watermark can and cannot prove
Marks you can see can be cropped, covered or re-photographed. An honest account of what a watermark establishes, what it only suggests, and the one case we have measured and not solved.
Tracing which copy of a document got out
If everyone gets a slightly different copy, a copy that turns up somewhere can be compared against the ones you sent. What that comparison gives back is a place to start looking, not a name.
What survives a screenshot, a crop, or a photograph
A mark spread across a page survives cropping and re-saving surprisingly well, and a photograph taken at a slight angle often destroys it. Where the line falls, and why it falls there.
How visible should a watermark be?
Stronger marks survive more handling and make the page harder to read. The trade is real and it is yours to make, but there is a point below which a copy that gets out can no longer be traced at all.
What a digital signature on a document actually proves
A valid signature proves nobody has altered the file since it was signed. Proving that the signer is who you think takes something the document itself cannot carry.
Doing it for real
How to watermark a PDF for one person
A step-by-step walk through marking a document for one named recipient — what each field does, which two are the only ones you have to fill in, and what to keep afterwards.
Checking that a document you were sent is genuine
If somebody has sent you a document that claims to be official, you can check it yourself, in your own browser, in about a minute — with no account, and without asking the sender anything.
What to do in the first hour after a document gets out
Keep the copy exactly as you found it, work out which version it is, and resist the two conclusions the evidence cannot support. A practical order to do things in.
Sending one document to forty people, traceably
One file sent to a group address can never be traced back to anybody. What has to change about the way you send it, and what that costs you in practice.
See for yourself that nothing is uploaded
Do not take our word for it. Open the panel your browser already has, run the tool, and read what was actually sent. Here is exactly what you will see and what to look for.
No technical background is assumed anywhere on these pages. Where a word is unavoidable it is explained the first time it appears, and where the answer is that you do not need us, the page says so. That is deliberate: what we claim here is limited by what the software can actually do, and where it cannot do something we would rather write it down than leave you to find out.