What encryption does this actually use?

Real AES-256 encryption via qpdf, the same open-source library used by many professional PDF tools — not a cosmetic password field that a basic PDF reader could ignore.

Does Documateo store my password?

No — the password is used only in memory during processing and is never written to any database or log. If you lose it, Documateo has no way to recover it, and neither does anyone else — that's what real encryption means. That's why we ask you to confirm you've saved it.

How do I choose a good password?

Length matters most. The strength bar gives a rough guide — it's an estimate, not a guarantee. Tapping 'Generate a strong password' makes a random 16-character one (without look-alike characters like 0/O or 1/l) that you can copy straight into a password manager.

Can I protect a PDF that's already password-protected?

Not directly — we'll tell you as soon as you add it. Unlock it first with your existing password, then apply the new one.

Can I stop people printing or copying instead of requiring a password to open?

Not yet — this tool locks the whole file behind a password to open it.

Protect PDF

Pro

Add a real password to a PDF with AES-256 encryption — the same standard professional tools use, not a cosmetic lock.

How it works

1
Upload the PDF you want to lock — we check it first, free, and tell you right away if it's already protected.
2
Choose a password, or tap Generate for a strong random one, and confirm it. Copy it somewhere safe.
3
Tick the box confirming you've saved it, then click Protect PDF.
4
Documateo encrypts the file with AES-256 on our servers and you download the password-protected PDF.

Protect PDF — frequently asked questions

What encryption does this actually use?: Real AES-256 encryption via qpdf, the same open-source library used by many professional PDF tools — not a cosmetic password field that a basic PDF reader could ignore.
Does Documateo store my password?: No — the password is used only in memory during processing and is never written to any database or log. If you lose it, Documateo has no way to recover it, and neither does anyone else — that's what real encryption means. That's why we ask you to confirm you've saved it.
How do I choose a good password?: Length matters most. The strength bar gives a rough guide — it's an estimate, not a guarantee. Tapping 'Generate a strong password' makes a random 16-character one (without look-alike characters like 0/O or 1/l) that you can copy straight into a password manager.
Can I protect a PDF that's already password-protected?: Not directly — we'll tell you as soon as you add it. Unlock it first with your existing password, then apply the new one.
Can I stop people printing or copying instead of requiring a password to open?: Not yet — this tool locks the whole file behind a password to open it.