Protect PDF
Add real password encryption (AES-256) to a PDF so it can't be opened without the password. Runs entirely in your browser — files are never uploaded to a server.
Click to upload or drag and drop
Select a PDF file
How it works
Your PDF is encrypted with AES-256 — the same modern, strong encryption standard used by professional PDF software — directly in your browser. The password itself is never sent anywhere; only you (and whoever you share the password with) can open the file afterward.
What the password controls
The password you set is needed to open the file. It is applied as both the opening password and the owner password, and every permission, including printing, copying and editing, is left allowed, so once someone has the password the document behaves like any other PDF. The tool does not offer separate restrictions. Encryption is AES-256 (the PDF 2.0 scheme). Recent mainstream readers open it, but older PDF software that predates AES-256 may refuse, so open the result in the program your recipient will use.
Steps and output
- Choose a PDF of up to 100 MB, type the password and type it again. Blank passwords and mismatched entries are rejected.
- The result is saved as protected.pdf. A PDF made mostly of images stays about the same size, but a small text-only PDF stored in compact form can grow noticeably, because the file is rewritten with each object stored separately.
- A PDF that already has a password is refused with a message. Use the Unlock PDF tool first, then protect the unlocked copy with the new password.
- If the password contains a character the tool can't encode, it reports an error; plain letters, digits and common symbols are safest.
Choosing and sharing the password
The strength of the password matters more than the algorithm: a short or guessable one can be guessed however strong the encryption is. Use a long random password from the Password Generator, store it in a password manager, and send it by a different route from the file, for example by message rather than in the same email. Nobody, including this site, can recover it. The file name, file size and the fact that a document exists are not hidden by encryption.
Frequently asked questions
What encryption does this use?
AES-256, the same strong, modern encryption standard used by professional PDF software — not a weaker legacy method.
Can I recover the password if I forget it?
No — the password is never stored anywhere, by this tool or anyone else, so there's no way to recover a forgotten password. Keep it somewhere safe.
What if the PDF is already password-protected?
This tool can't add a new password on top of an existing one — unlock the PDF first, then protect it with the new password.
Does the password stop people from printing or copying?
No. It controls opening the file only. After someone enters the password, printing, copying and editing are all permitted, because this tool sets no restrictions.
Will every PDF reader open the protected file?
Current browsers and mainstream PDF programs read AES-256 files. Very old software that predates AES-256 may not, so test the file in the reader the recipient will use.
Will the protected file be bigger than the original?
It depends on the file. A PDF made mostly of images stays about the same size. A small text-only PDF stored in compact form can become noticeably larger, because the file is rewritten with each object stored separately.