Password protect your PDF with AES-256
Set a password that must be entered to open the file, and decide whether readers may print, copy or edit. The encryption runs in your browser, so the file is never uploaded.
- Files never leave your browser.
- No account needed
- No watermark added
- Works on any device
How it works
Step 1: Choose the PDF you want to protect.
Step 2: Enter an open password, an owner password, or both, and confirm them.
Step 3: Choose what readers may do: print, copy content, edit or annotate.
Step 4: Select Protect PDF and download the encrypted file. Test it by opening it before you send it.
What protecting a PDF does
Protecting a PDF encrypts its contents. Without the right password the file cannot be opened, and a copy sent to the wrong person is just unreadable data. The tool uses AES-256, currently the strongest encryption in the PDF format, applied by QPDF, a well-established open-source PDF library that we run inside your browser as WebAssembly.
You can set two different passwords. The open password (sometimes called the user password) is the one a reader must type to view the document at all. The owner password controls the permissions: printing, copying content and editing or annotating. You can set either one or both. If you set only an owner password, the file opens freely but the restrictions apply.
Because the work is done on your device, neither the file nor the passwords are sent to a server. The result is a new encrypted PDF; your original stays unencrypted, so store it safely or delete it.
Why use this tool
Strong AES-256 encryption
The contents are encrypted with a modern algorithm, not an obfuscation trick that a reader can simply switch off.
Open and owner passwords
Require a password just to view the file, or leave it open but restrict printing, copying and editing.
Passwords stay in your browser
Neither the document nor the passwords you type are transmitted, so sensitive files are encrypted before they ever leave your device.
Works with common readers
Password-protected PDFs open in mainstream viewers on desktop and mobile, which ask for the password on opening.
Common uses
Emailing payslips or tax documents
Encrypt each document before attaching it, so a mistyped address or an intercepted email does not expose anything.
Sharing a contract draft
Send a draft to a counterparty and give them the password in a separate message or on a call.
Uploading to shared storage
Add an open password to a file that goes into a team drive or a cloud folder that more people can browse than should read it.
Medical or student records
Protect a report that must reach a patient, a parent or a school by email or a messaging app.
Archiving sensitive scans
Lock scanned ID and bank documents before they are stored on a laptop or a USB stick that could be lost.
Open password or owner password
The two passwords do different jobs, and choosing between them is the most important decision here. An open password is real access control: without it, the contents cannot be read, and all viewers enforce that because the data itself is encrypted.
An owner password is about permissions. It lets you mark a file as not printable, not copyable or not editable while still letting everyone open it. Those flags are a request that PDF software may honor: mainstream readers follow them, but a tool built to ignore them can. Use an owner password to discourage casual copying or editing, and an open password when the content must be kept from unauthorized eyes.
You can set both. Then a reader needs the open password to view the file, and the owner password is what a person would use to change the permissions later.
- Sending a confidential document to one person: use an open password.
- Publishing a read-only manual you would rather not see edited: use an owner password with editing disabled.
- Both together: use different values, so that sharing the open password does not hand over control of the permissions.
Choosing and sharing a password properly
AES-256 is far stronger than any password you will type, so the password is the weak point. Use a passphrase of several unrelated words or at least 12 characters mixing letters and digits; avoid names, birthdays and the file name.
Send the password through a different channel than the file. If the PDF goes by email, give the password by phone, in a messaging app or in person. Sending both in one email protects only against a lost attachment, not against a mailbox breach.
Store the password in a password manager. Because the tool runs in your browser and never sees the password, there is no reset link and no recovery service. If the password is gone and no unlocked copy exists, the document is gone.
The order of operations matters
Encrypt as the last step. Several other tools on this site, such as Merge PDF and Compress PDF, need an unlocked file, so you would need to unlock it first with Unlock PDF and the password. Finish your edits, add a watermark if you need one with Watermark PDF, remove hidden details with Remove PDF Metadata or Sanitize PDF, and only then protect the file.
Finally, open the protected copy yourself, in a different viewer if you can, and confirm that the password works and that the permissions you set are as you intended before you send it.
Supported formats
- Input
- One PDF file (.pdf).
- Output
- One AES-256 encrypted PDF file.
Very old PDF software may not support AES-256.
Good to know
- A lost password cannot be recovered. We never see your passwords and cannot reset them, and neither can anyone else, so keep the original and record the password safely.
- Permission limits (printing, copying, editing) are only honored by cooperating PDF software. A program that ignores them can bypass them, so they are not a hard lock.
- The strength of the protection depends on the password. A short or guessable password can be attacked by trial and error, whatever the encryption.
- Very old PDF viewers may not be able to open files encrypted with AES-256.
Your files never leave your browser
This tool runs entirely on your device using your browser. Your files are not uploaded to our servers and are not stored anywhere. Closing the tab discards everything.
Frequently asked questions
Is my PDF or my password uploaded when I protect it?
No. The encryption is done by QPDF running in your browser, so the file and the passwords stay on your device.
What happens if I forget the password?
The file cannot be opened. We do not receive your passwords and cannot recover or reset them, and AES-256 cannot be broken by guessing in practice. Keep the original unprotected file or store the password safely.
Can someone remove the printing or copying restrictions?
Sometimes, yes. Permissions are enforced only by cooperating PDF software; a program that ignores them can get around them. If the content must stay secret, set an open password instead of relying on restrictions.
What is the difference between an open password and an owner password?
The open password is required to view the file. The owner password controls permissions such as printing, copying and editing. You can set one or both.
Which encryption does the tool use?
AES-256, the strongest standard encryption available in the PDF format, applied by QPDF.