Protect PDF
Add password protection to PDF files online for free. Encrypt your PDF with RC4-128 encryption to restrict who can open, print, or copy it.
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Choose PDFAbout Protect PDF
Secure your PDF documents by adding password protection directly in your browser - nothing is uploaded to any server. Set an open password that must be entered to view the PDF, control print and copy permissions, and optionally set a separate owner password. Your file is encrypted using RC4-128, the standard PDF encryption compatible with Adobe Acrobat, Chrome, Apple Preview, and all major PDF viewers.
What is Protect PDF?
Some documents should not open without a password — pay slips, contracts, tax paperwork, anything with personal or financial detail. Protect PDF adds password security to a PDF so that only someone with the password can open and read it. It turns an ordinary file into one you can email or store without worrying about who else might see it.
The protection is applied in your browser, which means the original document is never uploaded to add the password. You choose a password, the tool encrypts the file, and you download a secured PDF. Share the file and the password separately, and your document stays for your intended reader’s eyes only.
Key features
Password-locked opening
The secured PDF asks for your password before it will display any content, so even if the file is forwarded, misplaced or intercepted, its contents stay unreadable to anyone without the password.
You set the password
You choose the password yourself and it is applied directly to the file. Nobody else sets it, and because the process is local, the password is not sent anywhere either.
Works in every reader
The encryption is part of the PDF standard, so the protected file prompts for a password in Adobe Acrobat, Preview, browsers and mobile apps alike — recipients do not need any special software.
Applied privately on your device
Encrypting locally means the unprotected document never leaves your computer, which is the whole point: you are not uploading a sensitive file to a server in order to secure it.
Who uses Protect PDF
HR and payroll
Password-protect pay slips and offer letters before emailing them to staff.
Accountants
Secure tax documents and financial statements shared with clients.
Freelancers
Lock contracts and invoices that contain personal or banking details.
Individuals
Protect scanned IDs, medical records and personal paperwork before storing or sending.
Benefits at a glance
- Keeps confidential documents unreadable without the password.
- Lets you email sensitive files with far less risk.
- Uses standard PDF encryption that every reader understands.
- Applies protection privately, with no upload of the original.
- Free, with no watermark and no account.
Tips and best practices
- Send the password through a different channel than the file — a message or call, not the same email.
- Use a strong, memorable password; if you forget it, the document cannot be recovered.
- Protect the final version after merging, signing or editing, so the locked file is the complete one.
- Keep an unprotected master copy in a safe place in case you need to make changes later.
- For documents you receive that are already protected, use Unlock PDF (with the known password) before editing.
The manual way vs. Protect PDF
Technical information
- Input format
- A PDF file
- Output format
- A password-protected PDF
- Security
- Standard PDF password encryption
- Processing
- In your browser — the original is not uploaded
The bottom line
Protecting a document before you send it is a basic habit that prevents a lot of trouble. Protect PDF makes it effortless: pick a password, get back a locked file, and share it knowing only the right person can open it. No software to buy, no upload of the sensitive original, and no cost.
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Your privacy is built in
Everything in Protect PDF runs locally in your browser — your data never leaves your device and is never uploaded to a server, so nothing you enter is stored or seen by anyone else. No account, no sign-up, no watermark, and completely free.