Encrypt PDF — Free Online
Encrypt any PDF file with AES password protection in your browser. No upload to any server, no signup needed. 100% free and completely private.
Encrypt your PDF with industry-standard AES encryption to prevent unauthorized access. Unlike most online tools, the encryption happens entirely in your browser — your password and file data never leave your device.
Drop PDF to password-protect
PDF • Max 200MB
How It Works
Add password protection to any PDF using AES-256 encryption — the same security standard used by banks, governments, and military organizations worldwide. The encryption process runs entirely in your browser using WebAssembly, so your PDF and password never leave your device.
Choose a strong password, confirm it, and download the encrypted PDF. Recipients will need the exact password to open and view the file. The original formatting, fonts, images, and all content are preserved exactly — only access is restricted.
This is a zero-knowledge encryption tool: your password exists only in your browser's memory during the encryption process and is never stored, transmitted, or logged anywhere. Even we have no ability to recover or see your password.
Features
- ✓AES-256 encryption — the gold standard for document security
- ✓Password-to-open protection prevents unauthorized access
- ✓Preserves all formatting, fonts, images, and embedded content
- ✓Handles PDFs up to 200MB
- ✓Zero-knowledge architecture — your password never leaves your device
- ✓Compatible with all PDF readers (Adobe Acrobat, Chrome, Preview, Firefox)
- ✓No signup, no account — encrypt unlimited documents for free
- ✓Encrypted output meets compliance requirements for secure document sharing
How to Use This Tool
- Upload the PDF document you want to protect. Any standard PDF file is supported.
- Enter a strong password and confirm it. Use a mix of uppercase, lowercase, numbers, and symbols for maximum security.
- Click "Encrypt" to apply AES-256 password protection. The process runs entirely in your browser.
- Download the encrypted PDF. Share it via email or cloud storage — only recipients with the password can open the file.
Perfect For
- →Businesses protecting confidential contracts, financial reports, and legal documents before sharing via email
- →Healthcare providers encrypting patient records and medical documents for HIPAA-compliant sharing
- →Accountants protecting tax returns, financial statements, and client documents during digital transmission
- →HR departments securing employee records, offer letters, and performance reviews
- →Legal professionals protecting case files, depositions, and privileged communications
- →Students and researchers protecting thesis drafts, unpublished research, and proprietary data
Under the Hood
The encryption uses the PDF 2.0 specification's AES-256 encryption handler. The user's password is used to derive an encryption key via a key derivation function, which then encrypts all stream and string objects in the PDF's object tree. The cross-reference table and metadata remain unencrypted (per spec), but all content — page streams, font data, images, and annotations — is encrypted.