Protect PDF Online
Protect PDF files with password encryption. Restrict printing, copying, and editing. Secure your sensitive documents.
Protect PDF is a free browser-based tool from SublimePDF. No registration, no file uploads, no watermarks — your files stay on your device throughout the entire process.
Drop your PDF files here
or click to browse — up to 50MB
Key Protect PDF Features
How to Protect PDF Online
Follow these simple steps to protect pdf your files in seconds.
Upload your PDF
Select the PDF document you want to protect with a password.
Set your password and permissions
Choose a strong password and select which actions to restrict (printing, copying, editing).
Protect and download
Click 'Protect PDF' and download your encrypted, password-protected document.
About the Protect PDF Tool
Keep your sensitive PDF documents secure with SublimePDF's Protect PDF tool. Add strong AES-256 encryption with password protection to prevent unauthorized access. Set separate passwords for opening and permissions, and granularly control whether users can print, copy text, or edit the document. Perfect for confidential contracts, financial statements, personal records, and any document that requires restricted access.
Why Use Protect PDF Online?
Apply AES-256 encryption — the same standard used by governments and financial institutions — directly in your browser. Set separate owner and user passwords, and granularly control permissions for printing, copying text, editing, and form filling.
- Completely free — no registration, no watermarks, no hidden fees.
- Private by design — files stay on your device; nothing is uploaded.
- Instant results — browser-based processing means no waiting for server queues.
- Works everywhere — Chrome, Firefox, Safari, and Edge on desktop, tablet, or mobile.
Privacy & Security
Your privacy matters. When you use SublimePDF's Protect PDF tool, all processing happens directly in your web browser using WebAssembly technology. Your files are never uploaded to our servers, never stored, and never seen by anyone but you.
About the PDF Format
PDF (Portable Document Format) was developed by Adobe and standardized as ISO 32000. It preserves document formatting across all devices and platforms, making it the universal standard for sharing and archiving documents.
Protect PDF — Frequently Asked Questions
What encryption is used?
What's the difference between open and permissions passwords?
Can I remove the password later?
What if I forget my password?
Protect PDF Guides & Tutorials
How to Password Protect a PDF
Protect sensitive PDF documents with a password to prevent unauthorized access. SublimePDF lets you add both an open password (required to view) and permission restrictions (printing, copying, editing).
How to Encrypt PDF Document
Encrypting a PDF restricts who can open, view, print, or modify your document by applying password-based protection and industry-standard encryption algorithms. This is critical for confidential business documents, client deliverables containing personal data, financial records, and legal files that must remain tamper-proof. SublimePDF lets you apply AES-256 encryption with customizable permission levels in seconds.
How to Lock PDF Editing
Protecting a PDF against unauthorized editing is essential when distributing contracts, official certificates, published reports, or any document where content integrity matters. Without editing restrictions, anyone with a PDF editor can alter text, move elements, or forge signatures. SublimePDF lets you apply permissions passwords that lock down editing capabilities while still allowing recipients to view and print the document.