Protect PDF
Encrypt your PDF with a password to prevent unauthorized access.
How to Protect PDF Files
1. Select and upload the PDF file you want to encrypt via the drop zone.
2. Set your custom user password in the password input field.
3. Click "Protect PDF" to compile standard filter encryption secure algorithms.
4. Save the generated password-locked PDF document using the "Download File" button.
FAQ
Q. Can I remove the password later?
Yes. If you know the correct password, you can upload the secure file to our PDF Unlock tool to strip the encryption and save it as an unprotected PDF.
Q. Can I recover a forgotten password?
No. For maximum security, we never store or log your passwords or files on our servers. Since we cannot retrieve it, please ensure you keep a backup record of your password.
Q. What encryption algorithm is used?
We apply standard cryptographic filter filters compatible with the PDF specification. All major PDF readers, such as Adobe Acrobat, web browsers, and mobile previews will correctly prompt users for the password.
Q. Is there any risk of password or file leakage?
None. The encryption processes are executed within a secured secure context. All data arrays and keys are immediately released from system memory once the compilation ends.
Q. Can I use Japanese characters or special symbols as passwords?
While Unicode is supported, we strongly recommend using standard ASCII characters (alphanumerics and basic punctuation) to avoid compatibility bugs on older PDF reader software.
Q. Will password protection decrease page quality?
No. We do not re-compress or rasterize internal pages. The tool merely appends security encryption dictionaries into the PDF structure, ensuring zero quality loss.
Q. What is the maximum file size?
You can upload and encrypt PDF documents up to 100MB.
Q. Will a password-protected PDF show up in search engine results?
No. Search engine crawlers (like Googlebot) cannot read the contents of a password-secured PDF, preventing it from being indexed or appearing in search results.
Q. Can I protect PDFs using smartphones or tablets?
Yes. Our platform is mobile-friendly and runs smoothly on iOS Safari, Chrome on Android, and iPadOS without needing external apps.
Q. Is it completely free to use without limits?
Yes, it is entirely free. There are no registrations, memberships, or trial limits.