Guide
What is the Protect PDF with password tool?
This tool adds a password to a PDF so the file cannot be opened without it. You drop in a PDF, type a password twice, and download a locked copy encrypted with AES-256, the strongest encryption in the PDF standard. The original file stays untouched.
| Item | Value | What it means |
|---|---|---|
| Encryption | AES-256 (PDF 2.0) | The current strongest PDF encryption, supported by modern readers |
| Open password | The password you set | Required every time someone opens the file |
| Page content | Unchanged | Text, images, and layout are identical to the original |
| Output | A new file named *_protected.pdf | The original PDF is not modified |
When it comes in handy
- Sending a contract, invoice, or quote by email and sharing the password through another channel.
- Handing over payslips, certificates, or HR documents that only one person should open.
- Storing tax or medical records in shared cloud folders without leaving them readable to everyone.
- Meeting a client's security policy that requires attachments to be password protected.
How to use
- Drop a PDF onto the upload area, or click it and select the file.
- Check the page previews to confirm it is the right document.
- Enter a password, then enter the same password again in the confirm field.
- Click "Protect & download". A locked copy downloads immediately.
For example, protecting contract.pdf with the password k9!mVx2# downloads contract_protected.pdf. Opening that file in any PDF reader now shows a password prompt, and only k9!mVx2# unlocks it.
Notes
- If you forget the password, the file cannot be recovered. There is no backdoor in AES-256 encryption.
- A PDF that already has a password cannot be protected again directly. Remove the old password first with the Remove PDF password tool, then set a new one here.
- Password strength matters: a short or guessable password weakens AES-256 in practice. Use 8 or more characters mixing letters, numbers, and symbols.
- To combine files before locking them, use the Merge PDF tool first and protect the merged result.
