What Is PDF Password Protector?
PDF Password Protector adds encryption and password requirements to your PDF files. Use it to secure confidential reports, financial statements, legal documents, or any file you need to share but want to restrict access to authorized readers only.
How to Use This Tool
Upload a PDF, set your desired password, and choose permission settings such as whether to allow printing or copying. The tool encrypts the document client-side and provides the protected PDF for download. Your original file and password never leave your browser.
Why Use PDF Password Protector?
Encrypting PDFs typically requires Adobe Acrobat or paid security software. This tool applies industry-standard PDF encryption entirely in your browser, so your sensitive files and passwords are never transmitted to any server. For a detailed walkthrough, see our step-by-step guide.
See also: If you need to remove a password rather than add one, the PDF Unlock reverses this operation for PDFs you have the rights to.
Frequently Asked Questions
What encryption does this use?+
AES-256 by default (revision 6, the method defined in PDF 2.0 and read by Acrobat X and later, Chrome, Firefox, Edge and current macOS Preview). You can switch to AES-128 (revision 4, PDF 1.6) for readers as old as Acrobat 7. RC4 is not offered: it is broken and was removed from PDF 2.0.
Is my PDF uploaded to a server?+
No. Encryption happens in your browser. Neither the PDF nor the password ever leaves your device.
What's the difference between user and owner password?+
The user (open) password is needed to view the document. The owner password is needed to lift the permissions, such as a block on copying. To let anyone view the file but restrict what they can do, untick 'Require a password to open the file' and set only an owner password.
Can a password-protected PDF be cracked?+
Not by breaking AES; both AES-128 and AES-256 are beyond brute force. The weak point is the password, which attackers guess offline once they have the file. Use at least 12 characters with a mix of letters, numbers and symbols, and do not reuse passwords. Note the length limits: AES-128 uses at most the first 32 characters and only Latin-1 letters; AES-256 accepts Unicode up to 127 bytes.
What encryption strength does the tool apply?+
Your choice in the Encryption menu: AES-256 (default) or AES-128. Both are applied to every stream and string in the file, and the download only appears once the tool has confirmed the output carries an encryption dictionary.
Can I set separate user and owner passwords?+
Yes. The Owner password field is separate from the open password. If you leave it blank, the tool generates a random 24-character owner password and shows it once, so the open password alone cannot remove your restrictions.
What permissions can I restrict?+
Seven flags: printing, changing content, copying text and images, adding annotations, filling forms, text access for accessibility tools, and assembling pages (insert, rotate, delete). These flags are enforced by the reader, not by the encryption: Acrobat and most viewers honour them, but some PDF tools ignore them once the file is open. Only the open password keeps the content itself private.
Is browser-side encryption as secure as desktop software?+
The file format is the same: an AES-256 file made here uses the same revision-6 security handler as one made in Acrobat, and qpdf, pikepdf and pdf.js read it the same way. The difference is where it runs: the PDF and passwords stay in your browser.
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Encryption is real AES (AES-256 by default, AES-128 for older readers) with separate open and owner passwords, not the cosmetic ZIP-style password some free converters apply. Seven permission flags let you allow printing while blocking copying, or allow viewing while blocking edits and form filling. We tested each mode on October 11, 2026: the AES-256 output is revision 6 (AESV3) and the AES-128 output revision 4 (AESV2) according to qpdf and pikepdf, both open in pdf.js only with the right password, and the owner password, not the open one, unlocks the permissions. Passwords and the file never leave your browser.