Protect PDF
Add password protection to your PDF files
Protect PDF encrypts your file with real AES-256 encryption, requiring the password you set to open it afterward — this isn't a cosmetic lock, it's the same standard PDF security handler professional tools use.
Choose a PDF file above — processing starts automatically.
How to use Protect PDF
- 1
Upload your PDF.
- 2
Enter the password you want to protect it with.
- 3
The PDF is encrypted with AES-256.
- 4
Download the password-protected PDF.
Everything you need to know about password-protecting PDFs
What does password protection actually do?
Adding a password encrypts the PDF so it can't be opened at all without that password — appropriate when a document contains sensitive information (financial details, personal records, contracts) and you want to be sure only the intended recipient can read it, even if the file itself ends up somewhere it shouldn't.
When you actually need this
- Sending sensitive documents by email, where the transport itself isn't guaranteed secure.
- Sharing financial or personal records that shouldn't be readable if the file is forwarded or misplaced.
Share the password separately
Send the password through a different channel than the file itself (a text message rather than the same email) — encrypting a file and then attaching the password in the same message defeats the purpose if that email is intercepted or forwarded as a whole.
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Frequently Asked Questions
What encryption does this actually use?
AES-256, applied through the PDF's standard security handler — the same mechanism used by professional PDF software, not a superficial lock that other tools can bypass.
Can I use a password that contains a comma?
No — a comma in the password is rejected upfront, since it would otherwise corrupt the encryption options and could permanently lock the file with no way to recover it, even with the correct password.
Can I protect a PDF that's already password-protected?
No — protecting an already-encrypted PDF is rejected with a clear error; unlock it first if you want to apply a new password.
Does this tool send my PDF to a server?
Yes — your file is uploaded securely, encrypted, and deleted from our servers within 1 hour.
Is this tool free to use?
Yes — completely free, with no signup required.