Is the Lock PDF tool free?

Yes. You can password protect PDF files online for free with no hidden fees or watermarks.

Are my files uploaded to a server?

No. Processing happens locally in your browser, so your PDFs never leave your device.

What is the difference between a User Password and an Owner Password?

A User Password is required to open the PDF. An Owner Password controls permissions such as printing, copying, and editing. Set both for maximum control.

Which encryption options are supported?

You can secure PDFs with AES-128 (highly secure and widely supported) or AES-256 (maximum security; older readers may not support it).

Will locking a PDF change its content or quality?

No. Password protection only updates the document’s security settings. Text, images, and layout remain unchanged.

What happens if I forget the password?

If you forget the User or Owner password for a securely encrypted PDF, it cannot be recovered. Store passwords in a reputable password manager.

Which PDF readers are compatible with locked files?

Most modern readers (e.g., Adobe Acrobat Reader, Foxit, Chrome’s built-in viewer) support AES-128 and AES-256 encryption. Very old readers may not open AES-256 files.

Can I allow printing but block copying or editing?

Yes. Set an Owner Password and choose granular permissions—for example, allow printing while disabling copying and modifications.

Can I remove a password later using this tool?

This tool adds protection. To remove a password, use an unlock tool and provide the correct Owner Password.

Lock PDF Online - Free Tool to Password Protect Your PDF Files

Lock PDF & Add Password

Q: Can I lock multiple PDFs at once?

Yes. Batch processing is supported so you can apply the same password and permissions to multiple PDFs and download them individually or as a ZIP.

Secure your PDF files with strong password encryption. Set user and owner passwords, and control document permissions like printing, copying, and editing. All processing is done securely in your browser.

Choose PDF Files

or drag and drop PDF files here (max 50MB per file, multiple files supported)

Set Passwords

User Password (to open PDF)

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Confirm User Password

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Owner Password (for permissions)

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If only Owner Password is set, PDF opens without password but permissions are restricted.

Encryption Level

Set Permissions (Requires Owner Password)

Allow Printing

Allow Copying Content

Allow Modifying Document

Allow Adding Annotations/Forms

Uncheck to restrict. Permissions are only effective if an Owner Password is set.

The Complete Guide to Locking PDF Files Online for Free

In today’s digital-first world, protecting your documents is more important than ever. PDFs are the most common file type for sharing contracts, invoices, reports, and personal records—but by default, they aren’t always secure. That’s where a PDF locker comes in. With our free online tool, you can password protect PDF files in seconds, keeping sensitive information safe from unauthorized access. This guide will show you why locking your PDFs matters, how to use our PDF password protector, and the best practices for securing your files.

Why Lock a PDF File?

Adding a password to your PDF isn’t just about extra security—it’s about control. Here’s why it’s smart to lock PDF files:

Confidentiality: Safeguard financial records, legal contracts, medical files, or business strategies from prying eyes.
Data Integrity: Stop others from making changes. With encryption, you can block editing, copying, or printing.
Compliance: Meet regulatory standards like GDPR or HIPAA by restricting access to sensitive data.
Protect Intellectual Property: Designers, writers, and researchers can prevent unauthorized distribution of their work.
Controlled Sharing: Assign a User Password for recipients and a stronger Owner Password to keep full control of permissions.

With our free PDF locker, you get these benefits without costly software or complicated steps.

How to Password Protect a PDF Online

Securing your PDF files with our tool is quick and easy. Just follow these steps:

Upload Files: Drag and drop your PDFs or click “Choose PDF Files.” You can lock multiple PDFs at once.
Set Passwords:
- User Password: Required to open the file.
- Owner Password: Lets you control permissions such as copying, printing, or editing.
Configure Permissions: Decide if users can print, copy, or modify the document. These settings require an Owner Password.
Select Encryption: Choose AES-128 (secure and widely supported) or AES-256 (maximum security).
Lock PDF: Click “Lock PDF(s)” and the tool will secure your files instantly—right in your browser.
Download: Get your password-protected PDFs individually or as a ZIP file.

In less than a minute, you can secure PDF files online with professional-grade protection.

User Password vs. Owner Password Explained

User Password: Prevents anyone from opening the PDF without authorization.
Owner Password: Controls what can be done with the file (printing, editing, copying). To change or remove restrictions, you must know this password.

For maximum control, set both. This way, your PDFs are locked to unauthorized users and restricted even for authorized viewers.

Granular Control with PDF Permissions

Our PDF password protector goes beyond basic locks. You can fine-tune how your document is used:

Allow or block printing.
Control whether text or images can be copied.
Restrict edits like page deletion or text changes.
Block annotations or form entries for finalized documents.

Applying the “least privilege” principle—granting only the permissions necessary—keeps your files safe and compliant.

AES Encryption: 128-bit vs. 256-bit

Every password you add uses strong encryption to secure your PDF:

AES-128: Industry-standard, highly secure, compatible with nearly all PDF readers.
AES-256: Extra-strong encryption, ideal for highly sensitive documents, but may not open in very old PDF software.

For most purposes, AES-128 is more than enough. Choose AES-256 if you handle critical or regulated data.

Who Should Use a PDF Locker?

Our free lock PDF tool is useful for everyone:

Individuals: Secure bank statements, IDs, or tax records.
Students & Educators: Protect theses, exam papers, and research material.
Businesses: Lock contracts, invoices, HR documents, or client proposals.
Lawyers: Keep case files and legal agreements secure.
Healthcare: Protect patient files and confidential records.
Freelancers & Creatives: Secure portfolios, invoices, or draft work before sharing.

Your Privacy Is Our Priority

Unlike other tools, our PDF locker runs entirely in your browser. That means:

Your files never leave your device—no uploads to external servers.
Faster processing since nothing is transferred online.
Greater security for sensitive or confidential files.
Cross-platform support—works on Windows, macOS, Linux, and mobile browsers.

Best Practices for PDF Security

Use strong, unique passwords for both User and Owner access.
Share passwords securely—never in the same email as the PDF.
Grant only necessary permissions (no printing or copying unless needed).
Keep your PDF software updated to avoid compatibility or security risks.
Always double-check the recipient before sharing sensitive files.

FAQs About Locking PDFs

1. Is this PDF locker really free?

Yes, our online PDF password protector is completely free with no hidden costs.

2. Are my files safe?

Absolutely. All processing happens on your device. Files are never uploaded to any server.

3. What if I forget my password?

If you forget your User or Owner password, you won’t be able to unlock the PDF. Store them securely using a password manager.

4. Can I unlock a PDF later?

No. This tool is for locking PDFs. To remove a password, you’ll need the correct Owner Password and a separate unlock tool.

5. Does locking affect quality?

No, locking only changes security settings. The content and quality remain exactly the same.

6. Can I lock multiple PDFs at once?

Yes, batch processing is supported. You can secure multiple files and download them individually or as a ZIP archive.

7. Which readers support locked PDFs?

Any modern PDF reader, including Adobe Acrobat, Foxit, Chrome’s viewer, and others. AES-256 encryption may not work on very old readers.

Conclusion: Lock PDFs Easily and Securely

Data protection is non-negotiable in today’s world. With our free online PDF locker, you can password protect PDF files in just a few clicks, apply strong AES encryption, and control permissions with ease—all without uploading your files to a server. It’s fast, secure, and accessible for everyone.

Ready to secure your documents? Lock your PDFs now and protect your sensitive information instantly.