PDF Password Protect
Add password protection to PDF files with AES-256 encryption. Upload one or multiple PDFs, set a password, and download the protected files. 100% free, works in your browser.
Drag & drop your PDF files here
or click to browse files
PDF files — one or multiple at once
When should I use this tool?
- Encrypt a tax return PDF before emailing it to your accountant
- Password-protect a salary slip stored in shared cloud storage
- Secure a signed contract copy before sending through a chat app
- Lock a confidential report before handing it to an external reviewer
How do I password-protect a PDF?
- 1Click the upload area and select the PDF you want to encrypt
- 2Enter a strong password and confirm it in the second field
- 3Choose whether to restrict printing, copying, or editing the file
- 4Click Encrypt and wait while the PDF is secured locally
- 5Download the protected PDF and store the password somewhere safe
Frequently asked questions
Which PDF encryption algorithm should I use?
AES-256 is the right choice for any new PDF in 2025. It is the strongest algorithm the PDF 1.7 specification supports, produces output that opens in every modern reader (Acrobat, Preview on macOS, Chrome's built-in viewer, iOS Books), and has no known cryptographic weaknesses for practical attack. AES-128 is adequate but offers no real advantage over AES-256 because both algorithms run at similar speed on modern hardware. RC4 variants (40-bit and 128-bit) are legacy from the 1990s and 2000s; they work but their keys can be brute-forced in minutes with modern GPUs, so avoid them unless you must open the file on a 15-year-old legacy PDF reader.
Do I have to set a password for opening AND for editing?
No — the two passwords are independent. You can set only an owner password (permissions password) to lock printing, copying, and editing while leaving the document open to any reader. You can set only a user password (open password) to block reading without it. Or you can set both to require one password to open and a different one to modify. Most public documents (whitepapers, sales sheets) use owner-only protection. Most private documents (tax returns, confidential contracts) use user-only or both. Our tool lets you set both passwords independently or check a box to use the same string for both.
What permissions can I restrict with the owner password?
The PDF specification defines six independent permission flags. Print: allow or disallow printing, with a sub-option for low-resolution print only. Modify: allow or disallow content changes. Copy: allow or disallow selecting and copying text or images. Annotate: allow or disallow comments, highlights, and form fill-in. Fill forms: allow form field entry even when general modification is blocked. Extract for accessibility: allow screen readers to read content even when copy is blocked (strongly recommended to leave enabled — blocking this disables accessibility assistants entirely). Our tool exposes all six flags with safe defaults: copy, print, and accessibility enabled; modification blocked.
Is the encrypted PDF crackable?
Not in practice if you use a strong password and AES-256. Password-protected PDFs are attacked with brute-force or dictionary attacks against the password, not against the AES algorithm itself. A random 12-character alphanumeric password takes centuries to brute-force on consumer hardware; a 10-word passphrase is effectively uncrackable. Weak passwords (dictionary words, names, dates) can be broken in hours. Avoid reusing passwords across files. Our tool does not enforce a minimum password strength because compliance with specific password policies varies by organization, but a live entropy meter shows the estimated cracking time so you can pick a password that matches your threat model.