How to Password Protect a PDF (Free, No Upload)
Add a password to a PDF so only the right people can open it. AES-256 encryption in your browser, optional print and copy limits, and sharing tips.
Quick answer
- Open Protect PDF, add your file, type a password twice (or tap Generate), then click Protect & Download.
- The file is encrypted with AES-256. Any standard PDF reader asks for the password before showing it.
- A lost password can't be recovered, so save it in a password manager and keep an unprotected original somewhere safe.
Contracts, payslips, medical records, tax returns — some PDFs shouldn't be readable by whoever happens to see the email or find the file. A password is the simplest protection: without it, the file can't be opened at all.
How to add a password to a PDF
- 1
Open Protect PDF
Go to Protect PDF and add the PDF you want to secure.
- 2
Set a password
Type it in both boxes. It needs at least 6 characters, and the strength meter shows how hard it is to guess. Or tap Generate for a random 16-character password, which is also copied to your clipboard.
- 3
Add restrictions (optional)
Open Restrictions to block printing, copying, editing, adding comments or filling in forms once the file is open.
- 4
Protect and download
Click Protect & Download. PDFDoco checks that the new file opens with your password, then saves it with -protected at the end of the name.
Good to know: Save the password somewhere safe before you close the page. PDFDoco never sees or stores it, so if it's lost, nobody — including us — can open the file.
AES-256 encryption, done on your own device.
Protect a PDFOpen password vs. restrictions
| Protection | What it does | How strong it is |
|---|---|---|
| Open password | Nobody can view the file without it | Strong — the contents are encrypted |
| Restrictions | The file opens, but printing, copying or editing is blocked | Weaker — they rely on the reader respecting them, and unlocking tools can remove them |
Use the open password for anything confidential. Restrictions are a useful extra — for example, to discourage someone from copying a price list into their own quote — but don't rely on them alone.
If you block any actions, you can also set an owner password, the password that controls those restrictions. It has to be different from the open password. Leave it empty and PDFDoco uses a random one.
How to choose a strong password
- Use 12 characters or more, mixing upper- and lowercase letters, numbers and symbols.
- Avoid names, birthdays and guessable words like "company2024" — password-cracking software tries those first.
- Not sure? Tap Generate and keep the result in a password manager.
How to share a protected PDF safely
Don't send the password in the same email as the file. If that email is forwarded or lands in the wrong inbox, both travel together. Send the password another way instead: a text message, a phone call or a messaging app.
The recipient doesn't need special software. Password-protected PDFs are a standard part of the format, and readers such as Adobe Acrobat, Chrome, Edge, macOS Preview and phone viewers simply ask for the password.
Before you protect a file
- Do your other edits first. Compress the file, add a watermark or number the pages before adding the password — PDFDoco's editing tools can't open a protected file.
- Already protected? PDFDoco won't add a second password. To change it, remove the old one with Unlock PDF, then protect the unlocked copy.
- Uploading to a form? Many online portals can't open protected PDFs and reject them. Upload an unprotected copy instead.
- Very old PDF software? If the recipient's reader dates from before 2008, turn on Compatibility mode (AES-128) under Restrictions.
Tip: Need the password off again later? Our guide to removing a password from a PDF explains how. You'll need to know the password.
Frequently asked questions
How secure is a password-protected PDF?
AES-256 encryption isn't practical to break. The weak point is the password: short or common ones can be guessed. A random password of 12 characters or more keeps the file effectively unreadable without it.
What happens if I forget the password?
The file can't be opened. PDFDoco never sees or stores your password, so it can't be recovered. Keep it in a password manager and hold on to an unprotected copy somewhere safe.
Does adding a password change how my PDF looks?
No. The pages, text, fonts and images stay exactly the same. Only the way the file is stored changes.
Is my file uploaded when I protect it?
No. The encryption happens inside your browser, so neither the document nor the password leaves your device.