How to Password Protect a PDF

Sensitive documents need protection. Whether you're sharing financial records, legal contracts, medical information, or confidential business plans, adding a password ensures only authorized people can open your PDF.

The challenge with most online PDF protection tools is ironic: they ask you to upload your sensitive document to their server in order to encrypt it. That defeats the entire purpose of security. PDFably solves this problem by encrypting files entirely in your browser.

Add Password Protection with PDFably

PDFably's Protect PDF tool encrypts your document without ever sending it over the internet. Your file stays on your device, and your password exists only in your browser's memory for the few seconds needed to apply encryption.

1. Open the Protect PDF tool
2. Upload the PDF you want to protect
3. Enter a strong password
4. Click Protect and download your encrypted PDF

What Makes a Strong Password?

A good PDF password should be at least 8 characters long and include a mix of uppercase letters, lowercase letters, numbers, and symbols. Avoid dictionary words, personal information like birthdays or names, and common patterns like "123456" or "password."

Consider using a passphrase — a series of random words like "correct-horse-battery-staple" — which is both strong and memorable. The stronger your password, the more resistant the encryption is to brute-force attacks.

Best Practices for Sharing Protected PDFs

Use separate channels. Never send the PDF and its password through the same medium. If you email the PDF, share the password via text message, phone call, or a secure messaging app. This way, someone who intercepts the email still can't open the file.

Share passwords temporarily. For one-time document sharing, communicate the password verbally or via a disappearing message. Don't create a permanent record of passwords alongside the documents they protect.

Consider your audience. Make sure recipients know the file is password-protected. Include a note in your email: "The attached PDF is encrypted. I'll share the password separately." Otherwise, they may think the file is corrupted when they can't open it.

When to Use PDF Protection

Financial documents: Tax returns, bank statements, investment reports, and salary information should always be encrypted before sharing electronically.

Legal documents: Contracts, settlement agreements, legal opinions, and case files contain privileged information that requires protection.

Medical records: Patient information, test results, and medical histories are protected by privacy regulations in most countries. Encryption adds a necessary layer of compliance.

Business confidential: Strategic plans, financial projections, merger documents, and proprietary research should be encrypted when shared outside your organization — and often within it.

Before Protecting: Prepare Your Document

Make sure your PDF is final before adding protection. Once encrypted, you'll need the password to make any further changes. Common preparation steps include:

• Merge all relevant documents into a single file
• Remove any pages that shouldn't be included
• Compress the PDF to reduce file size for easier sharing
• Fix page orientation so all pages display correctly