Protect PDF
Encrypt your PDF with a strong password.
or click to browse — supports PDF files up to 100MB
How to use
- 1 Drop or click to upload your file
- 2 Adjust options if shown
- 3 Click Run Tool
- 4 Download your result instantly
- ✓ Files up to 1GB
- ✓ Unlimited jobs/hour
- ✓ Batch processing
- ✓ Priority support
Files are processed securely and permanently deleted within 1 hour. We never store, read, or share your documents.
Why this works
Add a password to a PDF so the recipient must enter it before opening or printing. Standard 128-bit AES encryption — the same lock corporate document managers use.
Password protection is the simplest form of document confidentiality and the most-asked-for. Common cases: a tax return going to your accountant by email, a salary letter going to a mortgage broker, anything containing PII that needs to travel as an attachment.
When you protect a PDF here, we apply AES-128 encryption to the document body. Anyone trying to open the file is prompted for the password by their PDF reader (Acrobat, Preview, Edge, Chrome, Firefox — all support encrypted PDFs out of the box). Without the password the file cannot be opened, the text cannot be extracted, and the document cannot be printed.
A few practical points to know.
The password is not stored anywhere on our side. We use it once during encryption and immediately discard it. If you lose the password, we cannot recover it — the document is unrecoverable. Pick a password you'll remember or store it in a password manager.
Send the password out of band. Don't email the password in the same thread as the encrypted file — if someone is in your email account, both are exposed at once. Send the file by email; send the password by text message, Signal, or in person.
Strong passwords matter more than the lock. AES-128 is uncrackable by brute force in any reasonable timeframe — but a weak password (`password123`, your dog's name, a date) can be guessed in minutes by an attacker who knows you. Use a 4+ word phrase or a password-manager-generated string.
If you later need to remove the password (because you forgot you set one, or you trust the recipient to handle it), use the Unlock tool with the original password.
How it works
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1Upload your PDFDrop the PDF you want to protect into the upload box.
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2Set a passwordEnter the password the recipient will need to open the file. Use at least 12 characters; a memorable passphrase (4 random words) is stronger than a short scrambled string.
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3Apply protectionPress Protect. The job finishes in 1–2 seconds.
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4Download the protected PDFYou'll get back a password-locked version of your PDF. Send the password separately (not in the same email).
Real-world uses
Accountants
Sending a client's tax return by email — encrypt the PDF so the document is unreadable in transit and storage.
HR teams
Salary letters, offer letters, and offer comparisons travel by email. Encrypt before sending.
Lawyers
Discovery materials that include client PII. Protect every PDF before sharing with opposing counsel.
Mortgage brokers
Applicants email bank statements, tax returns and pay stubs. Re-protect with a known password before forwarding to lenders.
Common questions
What encryption strength do you use?
AES-128 — the standard for password-protected PDFs across Adobe Acrobat, Apple Preview, and corporate document managers. Uncrackable by brute force in any reasonable timeframe.
Can you recover a lost password?
No. We don't store passwords — they're used once and discarded. If you forget the password, the PDF cannot be recovered. Use a password manager or pick a memorable passphrase.
Will any PDF reader prompt for the password?
Yes. AES-encrypted PDFs are a standard format. Adobe Acrobat, Apple Preview, Microsoft Edge, Chrome, Firefox, and every mobile PDF reader will prompt the recipient.
Should I email the password with the file?
No. Send the password out of band — by text message, Signal, or in person. Sending both in the same email defeats the protection if the recipient's email account is ever compromised.
Can I protect against printing or copying only, not opening?
PDFRun's Protect tool sets the open-password (must enter to view). PDF supports a separate set of permission flags (block printing, block copying) but these are easily stripped by most PDF editors and provide weak protection. The strongest protection is the open-password.
How do I remove a password later?
Use the Unlock tool with the original password. We do not unlock PDFs without the password — that would defeat the encryption.