Protect PDF

Runs in browser PDF Security & Privacy

Add an open password, restrict what readers can do with an owner password, or both. Encryption is AES-256 (PDF 2.0) or AES-128, applied locally; the password never leaves your device.

Privacy: Processed locally in your browser. Your file is not uploaded.

How do PDF passwords, permissions and redaction work?

PDF encryption (ISO 32000, AES-256 in current files) has two passwords: the user password opens the document, the owner password controls permissions such as printing, copying and editing. Permissions are advisory flags that compliant readers honour, not a cryptographic barrier. Redaction is different from covering: a black box drawn over text leaves the text in the file, whereas true redaction removes it from the content stream — and metadata, attachments and thumbnails can leak what the pages no longer show.

Security note: Before sharing a redacted or "cleaned" PDF, inspect its metadata and text layer: what a viewer cannot see may still be in the file. Permissions stop honest readers, not determined ones.

Read the guide: How to Edit a PDF Without Uploading It

Only the open password stops someone opening the file; restrictions alone let anyone open it and rely on the reader to honour them.
Open passwordRestrictions
NoneSet
NoneNot protectedThe tool needs an open password, restrictions or bothOpens for anyoneCompliant readers block what you restricted; the owner password lifts it
SetLocked by the open passwordOnce open, printing, copying and editing are all allowedPassword first, then restrictionsThe restrictions stay advisory, even behind an open password
Two passwords
Open password needed to view the file at all. The real protection.
Owner password lifts the restrictions, which are advisory flags that compliant readers honour.

How to use Protect PDF

  1. Drop a PDF.
  2. Enter and confirm the open password, and/or tick "Restrict what readers can do" and set permissions.
  3. Choose the encryption.
  4. Click "Protect PDF" and download.

Protect PDF features

  • AES-256 (PDF 2.0) or AES-128 encryption
  • Open password, owner password, or both
  • Permissions: print (full / low-res / none), copy, modify, annotate, fill forms, assemble, accessibility
  • Generated owner password shown once when you leave it empty
  • Passwords never leave your device
  • Local processing

Protect PDF example

Read-only distribution copy

Input:

No open password; restrict: printing allowed, copying denied, modifying denied; owner password: (empty → generated)

Output:

brochure-protected.pdf — opens without a password, copy/edit disabled; the generated owner password is shown in the notes

Frequently asked questions about Protect PDF

What is the difference between the open password and the owner password?

The open (user) password is needed to view the file at all. The owner password lifts the restrictions — printing, copying, editing — and is what an editor asks for before changing them. You can set either or both.

Which encryption is used?

AES-256 (PDF 2.0, revision 6) by default; AES-128 if the file must open in readers older than 2017. RC4 is not offered because it is broken.

Are permissions enforced?

Well-behaved readers respect them, but permissions are only as strong as the reader’s cooperation; anyone with the owner password — or a tool that ignores the flags — can remove them. An open password is the real protection.

Is my PDF uploaded to a server?

No. The file is opened and processed by your browser with WebAssembly and JavaScript; nothing is sent to Mutqan Soft or anyone else. Close the tab and the file is gone. Downloading the result needs a free account — no subscription, no payment.

Can I use it on a password-protected PDF?

Yes, if you know the password: the file list asks for it once and every operation then works on the decrypted pages. The output is saved without a password unless you protect it again.

Technical notes

Encryption uses @cantoo/pdf-lib’s standard security handler: AES-256 (V5/R6, SHA-256 based key derivation) or AES-128 (V4/R4). Strings and streams are encrypted with per-object keys; the file is saved with object streams, which the encrypting writer requires. Permission bits are written to /P and enforced by conforming readers.

References