Is Encrypt PDF private?

Everything runs locally in your browser. Your files are never uploaded to StackPDF servers.

Do I need an account to use Encrypt PDF?

No. StackPDF is free to use without signing up or creating an account.

Does Encrypt PDF work offline?

After the page and libraries load, processing happens on your device. A connection is only needed to load the app the first time.

What is the difference between open and owner passwords?

The open (user) password is required to view the PDF. The owner password unlocks full control and is what enforces permission limits like no printing or no editing. Without a distinct owner password, most readers treat the open password as full access.

Can I re-encrypt a PDF that already has a password?

Yes. Enter the current password so the tool can decrypt and rebuild the file, then apply the new password and permissions. Re-encrypting without unlocking first would corrupt the page content.

Are permission limits DRM?

No. Print/copy/edit flags are respected by standard PDF readers, but they are not unbreakable DRM. Do not rely on them against a determined recipient who has the file.

Is password protection free with unlimited files?

Yes. Lock as many PDFs as you need with no account and no upload paywall — encryption never sends your file to our servers. Soft browser-safety size limits still apply.

Does Encrypt PDF upload my document?

No. Passwords and ciphertext are produced in your browser. That matters when the reason you are locking the file is that the content is sensitive in the first place.

What if I forget the password?

StackPDF cannot recover a lost password. Keep a copy of the unprotected original in a safe place, or use a password manager. Remove Password only works when you still know the open or owner password.

Encrypt PDF

Password-protect PDF files.

How it works

1Open a PDF (enter the current password if it is already locked).
2Set an open password and confirm it; check the strength meter.
3Optionally choose a restriction preset (print, copy, edit limits).
4Add a distinct owner password when you enforce those permissions.
5Run encrypt and download the password-protected PDF.
6Share the password through a separate channel from the file itself.

About

Encrypt PDFs with an open password and optional permission limits (print, copy, edit). Already-locked files can be re-encrypted when you know the current password — everything runs in your browser.

Set a password recipients must enter to open the file, optionally add a separate owner password, and pick restriction presets when you want standard readers to discourage printing or editing. A strength meter helps you avoid weak passphrases before you download the locked PDF.

Encryption on-device means the unprotected source never uploads to StackPDF for “processing.” You still control password distribution out of band.

Common use cases

Lock a contract PDF before emailing it outside your organization
Password-protect tax or medical PDFs on a shared computer
Re-encrypt a file with a new password after a shared secret changes
Discourage printing or editing with owner-password permissions
Add a password after merging or compressing a sensitive packet

Password-protect PDFs without a server

Uploading a confidential PDF to a website so that site can “add a password” defeats much of the point. Local encryption reads the file in your tab, applies standard PDF security, and writes a locked copy for download.

Use a strong open password and send that password through a different channel than the file (messenger vs email, for example).

Open password, owner password, and permissions

The open password gates viewing. Permission flags (print, copy, modify) are meaningful when a separate owner password is set and the recipient uses a reader that honors them.

Treat permissions as a seatbelt, not a vault door. They reduce casual misuse; they are not a substitute for withholding the file from untrusted parties.

When cloud security products still apply

Enterprise rights management, watermarking tied to identity, revocation, and audit logs require server-side systems. Consumer password encryption does not provide those controls.

For everyday “lock this before I email it” jobs, browser-local Encrypt PDF is enough — free, private, and free of an account wall.