About the Protect PDF
Tezmy's Protect PDF tool locks a PDF with a password, so it can only be opened by people you give the password to. Files are encrypted with AES-256, the strongest standard PDF encryption, or AES-128 for very old PDF apps. You can also limit printing, copying text and editing. After protecting the file, the tool opens it again to check that it really asks for the password. It all happens in your browser, so your document is never uploaded, and neither is your password.
Updated October 2026
How to use the Protect PDF
- 1Click Select PDF file, or drop your PDF on the page.
- 2Type the password to open the PDF, twice.
- 3Optionally untick Print, Copy text or Edit to limit what people can do.
- 4Click Protect PDF.
- 5Download the protected PDF and keep the password somewhere safe.
When to password-protect a PDF
Send the password in a different way from the file, for example by text message or a phone call, so someone who gets hold of the email doesn't get both.
- Sending bank statements, payslips, tax forms or ID documents by email.
- Sharing contracts, medical letters or HR documents with one person.
- Storing private documents in shared folders or cloud drives.
- Sending price lists or reports that shouldn't be forwarded freely.
How the protection works
A PDF with an open password (also called a user password) is encrypted: its text, images and pages are scrambled with a key made from your password. PDF apps ask for the password, unscramble the file and show it; without the password the contents are unreadable. This tool uses qpdf, a widely used open-source PDF library, running inside your browser, and applies the standard PDF encryption that Adobe Acrobat and other PDF apps understand.
After encrypting, the tool opens the new file twice as a check: once without a password, which must fail, and once with your password, which must work. Only then is the download offered.
Choosing a good password
- Use 12 characters or more. A few unrelated words with a number or symbol are easy to remember and hard to guess.
- Don't reuse your email or bank password.
- Use letters, numbers and common symbols. Emoji aren't allowed, because many PDF apps can't type them.
- The hint under the password box shows if it looks weak, okay or strong.
Limits on printing, copying and editing
Untick Print, Copy text or Edit to switch those off for people who open the file with the open password. Screen readers are still allowed, so the document stays accessible to people who are blind or partially sighted.
Be aware that these limits depend on the app respecting them. Mainstream apps do, but they can't stop someone from taking screenshots or using tools that ignore them. The open password, by contrast, is real encryption.
On a phone or computer, and private
Protect PDF works in any modern browser on Windows, Mac, iPhone, Android and Chromebook. Online PDF services usually upload your file and your password to their servers; here both stay on your device, which is exactly what you want for documents private enough to need a password. When the file is big, shrink it with Compress PDF before you lock it, and sign it with Sign PDF so people know who agreed.
Features
- AES-256 encryption (AES-128 for old apps)
- Optional print, copy and edit limits
- Checks the result asks for the password
- Keeps text, links and bookmarks as they were
- No sign-up, no watermark
- Private: file and password stay on your device
Frequently asked questions
How do I password-protect a PDF for free?
Select your PDF, type a password twice and click Protect PDF. Download the new file. From then on, every PDF app asks for that password before showing the document.
How secure is the protection?
The file is encrypted with AES-256, the strongest encryption in the PDF standard. The contents can't be read without the password. The real weak spot is the password itself: short or common passwords can be guessed by trying many options, so use at least 12 characters with a mix of letters, numbers and symbols.
What if I forget the password?
It can't be recovered, by us or anyone else: the password isn't stored anywhere. Keep your original, unprotected file, and save the password in a password manager.
What do the print, copy and edit options do?
They ask PDF apps not to allow printing, copying text or editing once the file is open. Adobe Acrobat, browsers and most mainstream apps respect them. They are a request built into the file rather than a lock, and some apps and tools ignore them, so don't rely on them alone for highly sensitive documents.
What is the permissions password?
When you limit printing, copying or editing, a second password (the permissions or owner password) is needed to lift those limits. It has to be different from the open password. Leave it empty and nobody can lift the limits on this copy.
AES-256 or AES-128?
Choose AES-256 unless the file must open in a very old PDF app. It works in all current apps, including Adobe Acrobat and Reader, Chrome, Edge, Firefox, Safari, and the iPhone and Android PDF viewers. AES-128 is still secure and opens in apps from the mid-2000s too.
Is my PDF or password sent to a server?
No. The encryption runs in your browser. The first time, it downloads the protection engine (qpdf, about 1.4 MB) from our site; after that, your file and password never leave your device.
How do I remove the password again?
Use Unlock PDF: type the password you know and save an unprotected copy. Or simply keep your original file.