Protect PDF

How to password protect a PDF in your browser

1. Open Protect PDF and drag your PDF onto the drop zone, or click to choose it from your device. Nothing is uploaded — the file is read by your own browser.
2. Type the password you want to require. This becomes the user password: the one a reader must enter before the document will open at all.
3. Confirm the password. There is no recovery step anywhere in this process, so write it down now — the encryption key is derived from the password itself and exists only in your browser.
4. Click Protect PDF. The file is encrypted with AES-256 on your device, which takes a second or two even for a large document.
5. Download the protected copy. Your original file is untouched; the new one asks for the password in Acrobat, Preview, Chrome, Edge and every mainstream reader.

Why use Protect PDF?

• 100% free with no limits, no sign-up and no watermarks.
• Private by design — your files are processed in your browser and never uploaded to a server.
• Fast and lightweight, with instant results even on a phone or a slow connection.
• Works everywhere — any modern browser on Windows, macOS, Linux, Android or iOS.
• Part of a full pdf tools suite, so related protect pdf tasks are one click away.

What people use Protect PDF for

• Password-protecting a PDF before emailing it, so the file is useless to anyone who intercepts the message or receives a mis-typed address.
• Encrypting a bank statement, payslip or tax return before uploading it to a portal that keeps a copy.
• Adding a password to a contract or NDA sent to a client, then sharing the password over a different channel such as a phone call.
• Protecting scanned identity documents — passport, driving licence, utility bill — before sending them to a landlord, bank or visa application.
• Locking a PDF you are sending as a printed-proof so it cannot be edited or re-saved without the password.

Protect PDF: limits and things worth knowing

• The PDF is encrypted with AES-256 using the password you choose. That is the same standard Acrobat applies, so the file opens normally in Acrobat, Preview, Chrome, Edge and every mainstream reader — it simply asks for the password first.
• There is no password recovery. Nobody, including us, can open the file without the password, because the key is derived from the password itself and never leaves your browser. Write it down before you close the tab.
• A user password (needed to open the file) is different from an owner password (needed to change permissions). This tool sets the open password, which is the one that actually protects the contents.
• Encryption protects the file, not the transmission. A password-protected PDF sent over plain email is safe from someone reading the attachment, but the filename and recipient are still visible in transit.
• To remove a password from a PDF you already own and can open, use Unlock PDF. It cannot break a password you do not know, and no legitimate tool can.

Sources

• ISO 32000-2 (PDF 2.0) overview

Is it private and secure?

Your privacy is built in. Protect PDF does all processing on your own device using client-side code, so your files are never transmitted, stored or seen by anyone — including us.

Network activity: none. Nothing is sent and nothing is fetched. This tool makes no network request at all once the page has loaded — which is why it keeps working if your connection drops.

You do not have to take that on trust — our privacy proof page publishes the Content-Security-Policy that enforces it, lists every third party it permits, and shows how to verify the whole claim yourself.

We also measured the competition. Our PDF upload audit recorded how many bytes each of 20 online PDF tools actually transmits: 12 of the 13 measurable services uploaded the whole test file, and Filevane transmitted 0.00 MB.

Learn more

PDF Passwords Explained: What They Do and Don't Protect — What a PDF password actually encrypts, why permissions restrictions are weaker than they look, and why a forgotten password means the document is gone.