Password Protect PDF — Free Online
Lock a PDF with a password to prevent unauthorized access, or remove a password from a document you own. Instant, free, no account needed.
- AES 128-bit encryption
- Lock or unlock — both in one tool
- No signup, no watermark, no page limit
Free forever · No account needed · Private & secure
Protect your PDF with a password, free
Sharing a PDF over email or cloud storage leaves sensitive documents open to anyone who intercepts the file. Adding a password means only people with the key can open it — no software license, no subscriptions, just a browser and this free tool. Whether you need to lock contracts, invoices, tax returns, or confidential reports, the protection is applied in seconds and the encrypted file downloads immediately.
This tool supports both user passwords and owner passwords. A user password controls who can open the document at all. An owner password lets the document open freely but restricts what viewers can do — it can block printing, copying text, or making further edits. Both levels of protection use 128-bit AES encryption (the PDF standard security handler), matching the same algorithm used by Adobe Acrobat.
Need to remove a password instead? Unlock mode works just as quickly. Upload the protected PDF, enter the current password to prove ownership, and download the unlocked version. Useful when a document needs to go to a printer, a portal that does not accept encrypted PDFs, or a colleague who cannot open password-protected files on their device.
PDF password protection, explained properly
What a PDF password actually does
Setting a user password encrypts the file's content streams with AES — the same cipher family used for banking traffic — so without the password, the text, images, and attachments are ciphertext, not just hidden behind a lock screen. This is meaningfully different from an owner password, which only sets permission flags (no printing, no copying) that many PDF viewers simply don't enforce. If the goal is real confidentiality, the user password is the one that matters.
The two-channel rule
Strong encryption is undone by weak handling. The single most common mistake is emailing the protected PDF and its password in the same thread — anyone who compromises that inbox gets both. Send the file one way (email, cloud link) and the password another (text message, phone call, a messaging app) so a single point of failure isn't enough to open the document.
A weak password undermines the same encryption from the other direction: modern hardware tries billions of guesses per second against short passwords, so "1234" on AES-256 is functionally unprotected. Four random words ("copper-otter-maple-batch") beat a short password with symbols, and are easier to communicate over the phone.
What passwords don't protect against
Encryption protects data in transit and at rest — not from someone you legitimately gave the password to. Anyone with valid access can screenshot, retype, or re-save an unprotected copy; that's a sharing-trust problem, not an encryption failure. And a password does nothing to redact content — if sensitive text needs to be permanently removed rather than merely locked behind a password, use actual redaction and verify the underlying text is gone, not just visually covered.
Why use this PDF password tool
AES-128 encryption
Passwords are applied using 128-bit AES encryption — the same standard used by Adobe Acrobat.
Lock & unlock in one tool
Add a password to restrict access, or remove an existing password you already know — both operations in the same place.
User & owner passwords
Set a user password to control document opening, and an owner password to restrict printing, copying, or editing.
No stored passwords
Your password is used only during processing and is never logged, stored, or transmitted beyond this session.
Up to 100 MB input
Handle large protected reports, legal documents, and multi-page portfolios in a single pass.
No signup required
Protect or unlock as many PDFs as you need — completely free, with no account, no watermark, no daily cap.
How to lock or unlock a PDF
- 1Upload your PDF
Drag-and-drop or click to upload the PDF you want to protect (up to 100 MB).
- 2Choose Lock or Unlock
Select "Lock PDF" to add a password, or "Unlock PDF" to remove an existing one (you must know the current password).
- 3Enter your password
Type the password you want to set (or the existing password to remove). Optionally add an owner password to restrict printing and copying.
- 4Download the result
Click Apply — the locked or unlocked PDF downloads instantly.
Technical details
| Encryption | AES 128-bit (PDF standard security handler, V4) |
|---|---|
| Password types | User password (opens file) or owner password (permission flags) |
| Operations | Lock (add password) or unlock (remove, requires knowing it) |
| Content changes | None — encryption wraps the file without altering layout or content |
| Max file size | 100 MB, no page limit |
| Compatibility | Adobe Acrobat, Preview, Foxit, and all major PDF readers |
| Price & account | Free, no signup; passwords never stored or logged |
When to password protect a PDF
- Protect a contract or legal agreement before emailing it to a client
- Lock tax returns and financial statements before storing them in cloud storage
- Restrict printing on a proof copy sent to a client for review
- Unlock a PDF to submit it to a government portal that rejects encrypted files
- Remove a forgotten owner password from a document you created
- Protect employee records or HR documents shared across a team
From our guides
Password Protect a PDF
User vs. owner passwords, the two-channel sharing rule, and what encryption can't stop.
Read the guideCompress a PDF for Email
Compress before encrypting — protected files should still be small enough to send.
Read the guideAre E-Signatures Legal?
Sign a document before locking it — the legal basics of electronic signatures.
Read the guideFrequently Asked Questions
What encryption standard is used?
What is the difference between a user password and an owner password?
Can I remove a password I forgot?
Will adding a password change the PDF content or layout?
Is there a page or file size limit?
Are my files kept private?
Can I password protect a PDF on mobile?
Does the protected PDF work in all PDF readers?
Should I share the password in the same email as the file?
Is a "restrict printing/copying" permission the same as a real password?
Can I merge or edit a password-protected PDF?
Your files stay private
Your privacy comes first. Browser-only tools run entirely on your device — your file never leaves your browser. Advanced tools that need heavier processing use secure server-side processing: the file is sent over an encrypted connection, handled in memory, and automatically deleted right after your download. Either way, we never store, share, or analyze your documents — and it stays free, needs no account, and adds no watermark.
Ready to secure your PDF?
Add or remove a password in seconds — free, with no watermark.
Protect PDF now