Protect PDF
Password Protect PDF Online – Encrypt with AES-256. No watermark added by QuickConvertOnline. Free, no account needed.
About Protect PDF
Protect PDF adds an open password to a PDF and encrypts it with AES-256, the strongest encryption method in the PDF standard. Anyone who opens the downloaded file must enter the password before they can see its pages.
Use it before emailing payslips, medical records, contracts or tax documents, or before storing them on a shared drive. Encryption is done by QPDF running as WebAssembly inside your browser, so neither the file nor the password leaves your device. You can protect up to 12 PDFs with the same password at once.
How to use Protect PDF
- Drop one or more PDFs onto the page or select Choose PDF.
- Type a password in New password and type it again in Confirm password.
- Select Apply to encrypt the file.
- Download the protected PDF and test it by opening it with your new password.
Features
- AES-256 encryption, supported by current PDF readers and browser viewers.
- Requires the password before the document can be opened.
- A confirmation field catches typing mistakes before you encrypt.
- Protects up to 12 PDFs with the same password in one run.
- Accepts an already protected PDF when you enter its current password, so you can replace an old password with a new one.
- Runs QPDF in an isolated worker in your browser; no server sees the file or the password.
Common uses
- Emailing payslips, bank details or tax documents.
- Sharing medical or legal records through a cloud link.
- Sending client deliverables that only the client should open.
- Archiving sensitive scans on a shared or portable drive.
Tips
- Use a long passphrase of several words; length matters more than special characters.
- Send the password through a different channel than the file, for example by text message instead of in the same email.
Frequently asked questions
How secure is AES-256 PDF encryption?
AES-256 is a modern encryption standard that is not practical to break by brute force. In practice, the password is the weak point: short or common passwords can be guessed by cracking software, so use a long, unique passphrase.
What happens if I forget the password?
This tool cannot recover it or reset the password on the protected file. The password is used locally and is not kept in a recovery account. Keep an unprotected original securely or store the password in a password manager.
Can I change the password of a protected PDF?
Yes. Enter the current password in the PDF password field and open the file, then type the new password twice and select Apply. The downloaded copy opens only with the new password.
Does it also block printing, copying or editing?
No. This tool sets a password that is required to open the PDF. It does not add separate permission restrictions, so anyone who knows the password can view, print and copy the document.
Is my input uploaded?
Tools run in your browser. Files, text and results are not uploaded to our servers and are cleared when you leave the tool.
Your privacy comes first
Tools run in your browser. Files, text and results are not uploaded to our servers and are cleared when you leave the tool.