Protect PDF
Add a password to your PDF to protect it from unauthorized access. Your files stay private and never leave your browser.
All processing happens in your browser. No uploads, no tracking.
About PDF Protection
Everything you need to know about protecting a PDF with a password
Load your PDF, enter a password and click Protect. RC4-128 encryption is applied directly in your browser, encrypting the full document content. The resulting file can only be opened with the correct password.
Step-by-step process:
- Click the selection area or drag and drop a PDF file
- Enter your password and confirm it in the second field
- Click 'Protect PDF' — encryption happens instantly in your browser
- Save the protected PDF and test it by opening it in any viewer
Technical specifications:
- • 128-bit RC4 encryption (PDF 1.4 standard)
- • Full encryption of PDF content (streams and strings)
- • Compatible with all professional PDF readers, Preview (macOS), Chrome, Firefox and all standard viewers
- • 100% local processing — the file is never uploaded to any server
- • No watermark or modification of original content
PDFSuite fully encrypts your PDF content using the RC4-128 standard, the same format used by professional PDF editors:
Access protection
- • The PDF content is fully encrypted
- • Viewers require a password before displaying the document
- • Compatible with all standard PDF viewers
- • PDF 1.4 standard — widely supported
✓ Ideal for: personal documents, invoices, contracts
Tips for a strong password
- • Use at least 8 characters for medium security
- • Mix uppercase, lowercase, numbers and symbols
- • Avoid dictionary words or personal data
- • Store your password in a manager (1Password, Bitwarden)
✓ A strong password is your best protection
Protecting PDFs locally ensures your password and content are never accessible to third parties. Unlike online services, there is no transmission of sensitive data.
Protection methods compared:
| Browser (PDFSuite) | Desktop Software | Online Services | |
|---|---|---|---|
| Privacy | Local files | Local files | Requires file upload |
| Cost | Free, unlimited | $50-200 license | Free with limits |
| Security | RC4-128 (PDF 1.4) | AES-256 available | Varies by service |
| File size limit | No limit | No limit | 10-50 MB typical |
| Speed | Instant (no upload) | Fast (local) | Depends on connection |
Key advantages:
- • 100% Private: Your password and PDF never leave your computer
- • No Installation: Works directly in your browser
- • Full Compatibility: Works with all standard PDF viewers
- • No Registration: Protect PDFs immediately without creating an account
- • Works Offline: Process files without internet (once the page is loaded)
Is the protected PDF compatible with all viewers?
Yes. We use the PDF 1.4 standard with RC4-128 encryption, compatible with professional PDF readers, Preview on macOS, the built-in viewers in Chrome and Firefox, and virtually all modern PDF viewers.
What happens if I forget the password?
You won't be able to open the PDF. The encryption is real — the document content is encrypted and there's no way to recover it without the password. Store it in a password manager.
Is my password sent to any server?
No. All encryption happens 100% in your browser. Neither your password nor your PDF content leaves your device. You can disconnect from the internet before using the tool and it will work just the same.
Can I protect large PDFs?
Yes, there is no artificial size limit. The only limit is your browser's RAM. PDFs of several hundred MB are processed without issues on modern computers.
Is RC4-128 encryption secure?
RC4-128 is the PDF 1.4 standard and provides effective protection for personal and business use. It's the same standard used by professional PDF editors. For most use cases, it's more than sufficient.
Can I protect a PDF that already has a password?
Not directly — you must first remove the existing password. If you have access to the original PDF without a password, you can apply a new one directly.