Password Protect PDF Online — Free & Secure
Add password protection to PDF files online for free. Encrypt your documents with RC4 128-bit security — 100% browser-based, no upload needed.
Drop your PDF file here
PDF up to 50 MB
How to Password Protect PDF Files
Upload your PDF file
Click the upload area or drag and drop a PDF file you want to protect. All standard PDF formats are supported.
Enter a strong password
Type a password and confirm it. Use a mix of uppercase, lowercase, numbers, and symbols for the best security.
Encrypt and download
Click 'Protect PDF' to encrypt your document. The password-protected PDF is downloaded instantly — no server upload required.
Store your password safely
Save your password in a secure location. Without it, the PDF cannot be opened. PDFFlare does not store or recover passwords.
Why Use PDFFlare to Password Protect PDFs?
100% Browser-Based Encryption
Your PDF files never leave your computer. Encryption runs entirely in your browser using pdf-lib — no server uploads, no third-party access.
Password Strength Feedback
A real-time strength indicator helps you choose a secure password. See whether your password is weak, medium, or strong before encrypting.
No Quality Loss
Password protection is added at the document level. Text, images, fonts, and formatting stay exactly as they are — zero re-encoding or compression.
No Signup Required
Start encrypting immediately — no account, no email, no watermarks. Just drop your file, set a password, and download the protected PDF.