or drop files here
- AES-256 lock. Everyday files stay on your device. A large Pro file is sent to our server.
- Strong AES-256 password encryption
- Optional print and copy restrictions
Lock a PDF with a real password
Some files should only open for the right person: a salary slip, a tax return, a signed contract, a scan of your passport. Protect PDF adds a password so the document asks for it every time someone opens it, and the contents are encrypted with AES-256. You can also block printing or text copying for extra control over what happens after the file is opened. Type the password twice to avoid typos, tap the eye icon to check it, and download a locked copy ready for email, shared folders, or a USB stick. Everyday encryption happens in your browser, on your device. A large Pro file is sent to our server. No ads, no sign-up, and no watermark on your file.
Password-protect your PDF in seconds
Lock contracts, IDs, and invoices with strong AES-256 encryption. Calm, ad-free workspace — set a password and download a protected PDF in seconds.
How to password protect a PDF online
- 1Upload the PDF you want to lock by dropping it into the box above or choosing it from your device.
- 2Type a password of at least 4 characters, then repeat it to confirm. Tap the eye icon to double-check what you typed.
- 3Set permissions: allow or block printing, and allow or block copying text.
- 4Tap Protect PDF and download your locked file. Share the password separately from the PDF.
Why lock your PDFs with PDFTrusted
- AES-256 encryption — the contents stay scrambled until the right password is entered
- Print and copy control — block printing or text copying when a file needs extra care
- Typo-proof setup — confirm the password and reveal it with one tap before locking
- Opens in everyday readers — recipients use the PDF apps they already have
- Clear file names — your download ends in -protected, so you know which copy is locked
- Private and free — encrypted in your browser on Free, or on our server for a large Pro file, with no ads and no sign-up
Protect PDF FAQ
Is it free to password protect a PDF?
Yes. Protect PDF is included in your free daily uses, for files up to 100 MB and 150 pages. There are no ads on the page and no watermark on your locked file. Pro gives you more daily jobs and room for larger documents if you secure files every day.
Is my PDF safe while it is being protected?
Yes. The password and encryption are applied right in your browser, on your own device, so everyday files are not sent to our servers to lock them. Your password is used only to lock the file. For Pro users, very large documents can use secure cloud processing, and those temporary files are removed automatically.
How strong is the protection?
Protect PDF uses AES-256, the strongest encryption option in the PDF standard. In practice, your password matters most: a longer phrase that mixes words, numbers, and symbols is far harder to guess than a short one. Twelve characters or more is a good habit for sensitive files like tax returns and medical records.
How do I password protect a PDF before emailing it?
Lock the PDF here, attach the protected copy to your email, and send the password another way, such as a text message or phone call. That way, a forwarded or misdirected email still cannot be opened by the wrong person. It is a simple habit for payslips, invoices, medical reports, and ID scans.
Can I lock a PDF on my iPhone, Android, or Mac?
Yes. Protect PDF runs in Safari, Chrome, Edge, and Firefox on phones, tablets, Mac, and Windows. Choose the file, set the password, and download the locked copy. There is nothing to install, and the protected file opens in the usual PDF apps once the password is entered.
How big can the file be?
Free covers PDFs up to 100 MB and 150 pages, which suits contracts, statements, and scanned records. Pro raises the limits for large reports and archives. If you want a lighter attachment, run the file through Compress PDF first, then protect the smaller version so it is ready for email.
What if I forget the password?
Keep a copy of the original, unprotected PDF somewhere safe, and you will always have access to your own document. A password manager is also a great place to store the passwords you set. Because the encryption is strong, the password is the only key to the locked copy, so saving it right away is the best habit.
How do I remove the password later?
Open the locked file in Unlock PDF, enter the password once, and download a copy that opens without it. That is handy when a document no longer needs protection, or when you want to edit, merge, or compress it. You can always protect it again afterward with a new password.