Protect PDF — Free Online Tool
Use instantly, free, with no signup. Your files are processed locally and never uploaded.
By the AllFileBox Team · Last updated: 2026-06-21
Drop your file here or click to upload
Free: up to 10MB • Pro: 100MB • Business: 500MB
Protect PDF is a free online tool that adds password encryption to a PDF, so only people who know the password can open and read the document.
Why password protect a PDF
Contracts, statements, and personal records often need to stay confidential. Adding a password encrypts the PDF so it cannot be opened without the key, which is essential when sending sensitive files by email or storing them in shared locations.
Strong, standard encryption
The tool applies standard PDF encryption tied to the password you choose. Anyone without the password sees only an encrypted file. Choose a strong, unique password and share it through a separate channel from the document itself.
How To Use Protect PDF
- Open Protect PDF in your browser.
- Drop your PDF onto the upload area.
- Enter the password you want to set.
- Confirm the password.
- Download the encrypted PDF.
Secure financial files
Secure financial files
Password protect a bank statement before emailing it to your accountant.
Protect contracts
Encrypt a signed agreement so only the parties can open it.
Lock personal records
Add a password to medical or ID documents stored in the cloud.
| Step | What it does | Note |
|---|---|---|
| Set password | Encrypts the file | Choose a strong one |
| Share PDF | Stays locked | Send key separately |
| Open later | Needs password | Unlock to remove |
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Key Features Protect PDF
Your Files Stay Private
All processing happens in your browser using WebAssembly. Your file is never sent to our servers. We have zero access to your files — guaranteed.