Treeet
How to use Protect PDF
- 01Add PDFsChoose files or drop them on the page.
- 02Done on your deviceNothing is uploaded. Adjust settings if you like.
- 03DownloadSave the result, or everything as one ZIP.
AES-256 encryption.
The same strong encryption banks use. Without the password the file can’t be opened.
Protect PDF adds a password to a PDF, so it can’t be opened without it. It’s free, uses AES-256 encryption, and runs in your browser, so the document and the password never leave your device.
How to password-protect a PDF
- Type a password in the Password box in the settings panel. Do this first, because the PDF is protected as soon as you add it.
- Turn Allow printing or Allow copying text off if you want to limit them. Both are on by default.
- Choose your PDF or drop it on the page.
- Press Save or Download. The file is named after the original with “-protected” added.
- If you added the PDF before typing a password, remove it with × and add it again.
What the settings do
The password is what really protects the file. The printing and copying limits are rules written into the PDF; mainstream readers follow them, but they don’t stop someone from photographing the screen. The limits are tied to a separate random key, so knowing the open password isn’t enough to lift them in apps that honor them.
Editing, filling in forms and adding comments aren’t restricted by this tool. Anyone who has the password can open the file and work with it as usual.
- Password: needed to open the PDF. The whole document is encrypted with AES-256, which modern PDF readers support.
- Allow printing: when off, PDF apps that respect the setting won’t print the file.
- Allow copying text: when off, those apps won’t let people copy text out of it.
When a password makes sense
If you only want to mark a document as confidential, Watermark PDF stamps every page instead. To keep pages out of a shared copy altogether, remove them with Delete PDF pages before you protect it.
- Emailing tax returns, payslips, medical records or anything with ID numbers.
- Storing personal documents in shared folders or cloud storage.
- Sending a draft you don’t want forwarded and opened by anyone who receives it.
Choosing a good password
- Use a long passphrase, such as four or five unrelated words, rather than a short word with a number.
- Don’t reuse the password from your email or bank.
- Send the password a different way from the file, for example the file by email and the password by text message.
- Keep an unprotected copy somewhere safe.
Common problems and fixes
- “Type a password first”: the Password box was empty. Type one, remove the file and add it again.
- “Password-protected” message: the PDF already has a password. Remove it with Unlock PDF, then protect it again with the new one.
- PDF/A archive files can’t be both encrypted and PDF/A, so the PDF/A label is removed from the protected copy. Keep the original if you need it for archiving.
Privacy
Encryption happens in your browser with pdf-lib. Treeet never sees your PDF or your password, so we can’t recover either for you.
Guides
At a glance
- Price
- Free. No sign-up, no watermark.
- Privacy
- Files are processed in your browser and never uploaded.
- Accepts
- You get
- Batch
- Convert many files at once and download them as a ZIP
- Works in
- Chrome, Edge, Firefox and Safari, on phones and computers
- Offline
- Keeps working without internet once the page has loaded
Questions
Is my PDF uploaded?
No. Everything happens in your browser, so your PDF never leaves your device.
What if I forget the password?
It can’t be recovered, by us or anyone. Keep an unprotected copy somewhere safe.
Is there a size limit?
Only your device’s memory. Even long PDFs take seconds on a computer.
How secure is AES-256?
AES-256 is a strong, widely used standard. The weak point is usually the password itself, so choose a long one that’s hard to guess.
Can I protect a PDF but still allow printing?
Yes. Leave Allow printing on. People who know the password can open and print the file.
Can I set a separate password just for editing?
No. This tool sets one password for opening the file, plus optional printing and copying limits.
Will the recipient need special software?
No. Common readers such as Adobe Acrobat Reader, Apple Preview and the PDF viewers built into modern browsers open AES-256 files. Very old readers may not.
Can I protect a PDF on my phone?
Yes. Type the password, choose the PDF from your phone and download the protected copy, all in your browser.
How do I remove the password later?
Use Unlock PDF and type the current password. It saves a copy that opens without one.