PDF TOOLS
Password Protect a PDF
Add an open password to a PDF using standard AES-256 encryption, so compatible viewers will ask for it before showing the document.
Quick answer: Choose the PDF, set a long password and confirm it, protect it, then open the result in a different viewer to test it before you send it.
Use Password Protect a PDF ↓Loading the tool…
How to use Protect / Unlock PDF
- Choose the PDFLeave the action on “Protect PDF with a standard password” and select the file. Nothing is uploaded; the file is read in this tab.
- Set and confirm a passwordUse a long passphrase rather than a short word. The strength meter is only a guide, so also check that you can retrieve the password later from a password manager.
- Protect and downloadName the output file and run the tool. Open the downloaded PDF in a second viewer or browser and confirm that it asks for the password.
- Share the password separatelySend the password through a different channel from the file, for example a phone call or a message app, never in the same email.
About this tool
A password on a PDF is the simplest way to stop a file being read by whoever happens to find it in an inbox, a shared folder or a lost laptop. This page adds that password in your browser, so the document and the password are never sent to a server, which is exactly what you want when the file is a payslip, a contract or a tax return.
Common uses: Create a normal password-protected PDF for sharing or unlock a PDF when you know its password and need an unprotected working copy.
Practical example: Use a long unique password, download the protected PDF, and test it in a separate PDF viewer before sending it. Keep the password separate from the file.
Important limitation: AES-256 protection may not open in very old PDF viewers. Password protection is not a substitute for secure storage, access control or a signature audit trail.
Protection runs in this browser tab with a library served from this website. The password and the document are never sent anywhere. Read the privacy information.
How it works
Protect writes a new PDF encrypted with your password using the standard PDF security handler; Unlock decrypts a PDF you can already open with its password.
Real-world uses
- Sending a sensitive document by email
- Removing a password you no longer need
- Locking a draft before sharing
What PDF password protection does and does not do
The tool applies the standard PDF security handler with AES-256 encryption and an open password. Any viewer that follows the PDF standard, including current versions of Acrobat, Preview, Chrome, Edge and Firefox, will ask for the password before it shows a page. Very old viewers may not support AES-256, which is why the advice on this page is always to test the result in a second application before you rely on it.
Protection is only as strong as the password. A short or common password can be guessed offline by anyone who has a copy of the file, because encryption cannot hide a weak password. A passphrase of four or five unrelated words, or a long random string from a password manager, is far stronger than a clever eight-character mix. There is no recovery: if you lose the password the document cannot be opened, and because the file never reaches a server, nobody here can reset it.
Remember what a password does not cover. It does not prove who wrote the document (that is a signature), it does not remove sensitive text you meant to delete (use Redact PDF first), and once someone has the password and a copy they can save an unprotected version. For regulated data, follow your organization’s own rules about storage and transfer. If you need to remove a password from a file you are allowed to open, use the Unlock mode on the Unlock PDF page.
Tips for better results
- Use a long passphrase and store it in a password manager.
- Share the password through a different channel than the file.
- Password protection does not replace secure storage.
Frequently asked questions
Can another PDF application open the protected file?
Yes. The output uses standard PDF encryption and is intended to open in compatible viewers such as modern browser PDF readers and desktop PDF applications.
What happens if I lose the password?
The password cannot be recovered by this browser tool. Keep it in a password manager or another secure location.
Are my files uploaded?
Protection runs in this browser tab with a library served from this website. The password and the document are never sent anywhere.
Can I unlock a PDF I forgot the password for?
No. Unlocking requires the correct password.
What encryption is used?
Standard AES-based PDF encryption. Very old viewers may not open it.
How strong should the password be?
Aim for at least 12 characters and ideally a passphrase of several unrelated words. Length matters more than symbols. Store it in a password manager so you can find it later.
Can the recipient open it on a phone?
Yes, current iOS and Android PDF viewers and mobile browsers support AES-256 PDFs. If a very old reader fails, ask the recipient to use a current browser or viewer.
Does protecting the file change its content or quality?
No. The pages are copied as they are and wrapped in encryption, so text, images and links stay the same. Run Compress PDF first if you also need a smaller file.