🔒 Protect PDF

Protect PDF – Secure Your Documents with a Password

Keep sensitive documents safe. Our Protect PDF tool lets you add password protection to any PDF — ensuring only authorized people can open, view, or edit your files.

2.4M+ PDFs Processed
17 Free Tools
0 Data Breaches
4.9★ User Rating

Drop your files here

or click to browse. Processing happens 100% in your browser.

🔒 Your file stays on your device. We never see it.

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How It Works

01

📤 Upload

Select your PDF.

02

🔒 Set

Enter and confirm password.

03

📥 Download

Get your protected PDF.

Features

🔒

Add Password

Set a strong password.

📄

Encrypt

AES-256 encryption.

Quick

Protect in seconds.

🔒

Private

Password stays local.

Perfect for: Legal professionals securing client files, HR teams protecting employee records, anyone sharing confidential documents.

The PDFDocStudio Difference

Before

Unprotected file • Anyone can open • Compliance risk

After

AES-256 encrypted • Password required • HIPAA ready

Use Cases by Profession

Technical Specifications

Encryption AES-256
Password Policy Minimum 8 chars
Method WebAssembly crypto module
Processing Method WebAssembly (WASM)
Browser Memory < 512MB allocated
Supported PDF Versions 1.4 through 2.0
Output Quality Lossless / 300 DPI
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Why Choose PDFDocStudio?

Feature PDFDocStudio Cloud Competitors
File Uploads ❌ Never ✅ Required
Account Needed ❌ No ✅ Often
HIPAA Friendly ✅ Yes ⚠️ BAA Required
Max File Size 50MB Varies
Price Free Freemium

Frequently Asked Questions

Why is there a 50MB limit?

Browser memory constraints cap safe WebAssembly processing at ~50MB per file. Larger files risk crashing the tab. We're optimizing streaming algorithms to raise this to 200MB.

Do you add watermarks to free outputs?

Never. Free outputs are identical to paid outputs. No watermarks, no ads injected into PDFs, no quality reduction.

How do I know the code hasn't been tampered with?

We publish our Subresource Integrity (SRI) hashes in our GitHub repository. You can verify the WebAssembly binary hash matches our open-source release.

What if my browser crashes during editing?

Since processing is local, a crash only affects the current session. Your original file remains untouched on your hard drive. Simply reopen the tool and re-upload.

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Ready to Protect PDF?

100% free. 100% private. 100% in your browser.

Protect Your PDF Now