Skip to the converter

Protect PDF, without the upload.

Lock a PDF so it asks for a password to open. The password is never sent anywhere, so we could not reset it if we wanted to.

  • Free, no sign-up
  • AES-256
  • Password stays on your device

Drop a PDF to protect

or choose from your computer paste with Ctrl V

Ready · PDF files · several at once0 bytes uploaded, ever

How to protect a PDF with a password

  1. Add your PDF

    Drop it above or choose it.

  2. Choose a password

    Type it twice. Write it down: it can't be recovered.

  3. Protect and download

    Save the locked file.

What stays and what doesn't

Locking adds a password and leaves the pages alone. This is the full list of what the lock changes:

  • the PDF/A mark

A digital signature is removed, only after you say so: any change to a signed file breaks the signature, so the file is held back until you choose to continue.

When it won't run

Five things stop a run before it writes anything, and each is said on the file's row. A PDF that needs a password asks for it there, and a wrong password is refused with a sentence that says so. A digitally signed PDF is held back until you choose to continue, because locking it would break the signature. A file that cannot be read is reported as damaged. A job too large for this device says so, and in every case nothing is changed and your original stays as it was.

  • The PDF already has a password. Unlock it first, then protect it again.Unlock PDF
  • That password is too long. Use 127 characters or fewer; some characters count as more than one.

Protecting a PDF: what to expect

Type a password twice and the PDF is locked with it: whoever opens the file is asked for the password first. The file is encrypted with AES-256, the strength current PDF readers support. The password can be up to 127 characters long; some characters count as more than one.

This locks the file against opening. It does not stop anyone who has the password from printing, copying or editing, and this page does not offer a way to forbid those. If people need to read a file but not change it, a password to open is not the right tool for that.

Write the password down before you press Protect. Your browser uses it to lock the file and then forgets it; nothing keeps a copy, so nobody, including us, can open the file again if it is lost. A PDF that already has a password is not locked a second time: unlock it first, then protect it again.

Questions

Are my PDFs uploaded?

No. Your PDFs are processed inside your browser, on your own phone or computer, and saved straight from this page. The reading at the top of the page counts every byte sent, and it stays at 0 B. The password is typed into this page and used by your browser to lock the file. It is not sent anywhere.

Can I stop people editing or copying it?

Not here. This adds a password to open the file. Anyone who has the password can still print, copy and edit.

What if I forget the password?

Nobody can open the file, including us. Write it down.

How strong is it?

AES-256 encryption, the strength modern PDF readers support.

Does it work on a PDF that already has a password?

No. Unlock it first, then protect it again.

More PDF tools

All PDF tools

Other things to do with a PDF

All tools