Protect PDF with a password
Encrypt a PDF on this device with a real open password and optional owner password.
At a glance: Input: 1 PDF · Output: 1 encrypted PDF · AES-256 · Original file unchanged
Use a real open password for confidentiality
SnackPDF writes PDF 2.0 AES-256 encryption locally in this browser. The open password is required by a reader before it can display the file; an optional owner password manages the permissions you choose. Passwords are cleared from the page after the operation.
Permissions are advisory. Conforming readers may honour the printing, copying, editing, annotation, form, accessibility and assembly choices, but nothing cryptographic prevents a determined tool from ignoring them.
Encryption is not redaction
Password protection does not remove anything. Anyone who can open the file can see all of its content, including text or images that were only covered by a rectangle. If content must be removed from the saved file, use Redact PDF content and review the result separately.
Open the downloaded result in another PDF reader and test the password before sending it. AES-256 needs a secure HTTPS context; SnackPDF throws an error instead of silently falling back to the weak legacy RC4 algorithm.
Privacy, cost and compatibility
- Uploaded?
- No. AES-256 encryption happens locally in this browser tab.
- Cost and account
- Free to use without an account or paid credits.
- Watermark
- None is added to the protected PDF.
- Offline
- Yes, after the application is ready for offline use and the page is served from a secure context.
- Mobile
- Supported mobile browsers can protect PDFs, subject to device memory and reader support.
- Important limit
- AES-256 requires Web Crypto in a secure HTTPS context. Reader permissions are advisory, and encryption does not remove or redact content.