PDF Password Protector Free Online
Add 128-bit RC4 password protection to any PDF you own. Set an open password, restrict printing and copying, and download the encrypted file instantly. Nothing is uploaded.
Add password protection to a PDF using standard 128-bit RC4 encryption (PDF 1.4). Optionally restrict printing and copying.
Drop your PDF here
or click to browse — .pdf files only
How to Add a Password to a PDF
- 1Upload your PDF by clicking Choose File or dragging it onto the tool.
- 2Enter an open password. Anyone who receives the file will need to enter this password to open it. Optionally set an owner password to control whether the recipient can print or copy text.
- 3Choose your permissions — allow or restrict printing and text copying — then click Protect PDF.
- 4Download the encrypted PDF. Share it safely knowing only recipients who know the password can open it.
Open Password vs Owner Password — Which Do You Need?
An open password encrypts the content so it cannot be opened without the password. Use this when the document must be kept confidential — only the right recipients can read it. An owner password controls what an authorised viewer can do with the document: print it, copy text, or extract pages. If you leave the owner password blank, this tool generates one automatically — so the permission restrictions you set are actually enforced by the PDF reader. For most use cases, setting only an open password is enough.
Why You Might Need to Password-Protect a PDF
Send Confidential Documents
Contracts, NDA agreements, financial statements, and HR documents often contain sensitive information. Protect them with a password before emailing so only the intended recipient can open them.
Restrict Printing
Prevent recipients from printing a digital-only document — useful for e-tickets, downloadable books, or any content where you want to limit physical reproduction.
Protect Proprietary Content
Technical reports, research papers, and product manuals may contain information you want to share selectively. A password gate ensures only approved readers access the content.
Prevent Copy-Paste
Stop recipients from copying text out of the document into other tools. Combined with a print restriction, this reduces casual redistribution of proprietary written content.
Secure Personal Records
Scan-to-PDF documents like passports, tax returns, and medical records stored in cloud drives or sent by email benefit from password protection in case of an account breach.
Academic and Exam Papers
Instructors can encrypt exam papers before distribution so they can only be opened at the right time using a password shared just before the exam begins.
Frequently Asked Questions
What encryption does this tool use to protect PDFs?
This tool uses PDF Standard Security with 128-bit RC4 encryption (PDF 1.4, Revision 3). This is the same encryption used by Adobe Acrobat 5 and later, and is widely supported by all major PDF readers including Adobe Acrobat, Preview on macOS, Foxit, and Evince. The encryption key is derived from your password using the standard PDF key-derivation algorithm (MD5-based with 50 iterations).
What is the difference between an open password and an owner password?
An open password (user password) prevents anyone from opening the PDF without entering the correct password — the content is fully encrypted. An owner password (permissions password) does not block opening, but signals to PDF readers which actions (printing, copying, editing) are restricted. This tool lets you set both: the open password encrypts the file, while the optional owner password controls permissions. If you leave the owner password blank, one is automatically generated to ensure your permission restrictions are enforced.
Can I restrict printing and copying without requiring a password to open the file?
Not with standard PDF encryption. The PDF specification links permissions to encryption — you cannot enforce restrictions unless the document is encrypted. To restrict copying or printing, you must also set an open password. If you only want to mark the document as restricted without a password, that can be done in PDF editors but is trivially removed and is not enforced by most readers.
Is my PDF file uploaded to a server?
No. All encryption runs entirely in your browser using JavaScript (the same MD5 and RC4 routines used by the PDF specification). Your file is loaded into browser memory and the encrypted copy is written directly to your downloads folder. Nothing is ever transmitted to any server. This is especially important for confidential documents such as contracts, financial statements, and personal records.
Will the protected PDF open on mobile and other PDF readers?
Yes, in most cases. 128-bit RC4 (PDF 1.4) is a broadly compatible standard that has been supported for over 20 years. Adobe Acrobat Reader (Android, iOS), Foxit, Preview (macOS/iOS), Microsoft Edge, and most PDF viewers handle it correctly. The one exception is some very old software (pre-2002). If you need compatibility with readers that use AES-256 encryption, you would need a desktop tool like Adobe Acrobat Pro.
What should I do if I forget the open password?
If you forget the open password to a PDF you protected, there is no built-in recovery mechanism — that is the point of encryption. Before locking an important document, store the password in a password manager. If you have a backup of the original (unencrypted) file, you can re-protect it with a new password using this tool.