I forgot the password — can it be recovered?

No. The password is real encryption applied locally, and nothing about your file or password ever left your browser, so there's no reset link and no way for anyone to recover it. Write the password down somewhere safe before you send the file — this is how most people lock themselves out.

How do I change or remove a PDF's existing password?

This protect mode can't open a file that's already encrypted because it doesn't ask for a current password. Run the file through Unlock PDF first (you'll need the existing password), then add the new one here — that two-step is also how you change a password.

Does the password also block printing and copying?

The same password is set as both the user password (required to open) and the owner password (which governs permissions), so one secret controls opening the document and its printing/copying permissions together.

Why is the protected copy slightly larger than the original?

Encryption in this build is incompatible with PDF object streams, so the file is re-saved without them, which can add a bit of size. That's expected and doesn't affect how the document looks or opens.

Is the encryption strong enough for truly sensitive files?

The document is genuinely encrypted, but its security is only as strong as the password you pick — a short or common one can be guessed or brute-forced offline. Use a long, unique passphrase for anything you'd be harmed by losing.

Protect PDF

Add a password to a PDF so it asks for it on open. In your browser.

PDFs are processed in your browser — neither the password nor the file is ever uploaded.

Choose a PDFNew password

Choose a PDF file.

What is Protect PDF?

Protect PDF is a free tool that adds a password to a PDF so it asks for one every time it's opened — useful for contracts, statements, and other sensitive documents. It processes the file entirely in your browser; neither the PDF nor the password is uploaded. Set a password and download the protected copy in seconds.

Key features

Adds an open password so the PDF prompts before opening
You choose the password; it can't be recovered if forgotten
Downloads a protected copy ready to send or archive
Works together with Unlock PDF to change an existing password

How to Password-Protect a PDF (Add a Password)

Adding an open password to a PDF means the file is encrypted on disk and won't display its contents until the right password is typed — useful before emailing a contract, a bank statement, a payslip, or medical paperwork. Anyone who intercepts or forwards the file sees only an encrypted blob. This tool does that conversion right in your browser: the PDF and the password both stay on your device.

Steps

Click Choose a PDF and select the file to protect.
Type the password it should require into New password. The button stays disabled until this field has at least one character.
Press Add password & download. You get back a new file named <original>-protected.pdf; the original on your disk is untouched.

Open that protected file in any PDF reader — Preview, Acrobat, Chrome, a phone — and it will prompt for the password before showing a single page.

How it works, and what "protected" covers

The file is loaded, encrypted with your password, and re-saved locally using the pdf-lib library. The same password is set as both the user password (the one required to open the document) and the owner password (the one that governs permissions like printing and copying), so a single secret controls everything. Because encryption in this build is incompatible with PDF object streams, the tool saves without them; that can make the protected file slightly larger than the original, which is normal.

The critical caveat: there is no recovery

An open password is real encryption, not a display trick, so if you forget it, the document cannot be opened — not by this tool, not by us, not by any "reset" link, because nothing about your file or password ever left your browser to be reset. Write the password down somewhere safe before you send the file. This is the number-one way people lock themselves out of their own documents.

Common snags

Re-protecting an already-locked PDF. This tool's protect mode doesn't ask for a current password, so it can't open a file that's already encrypted. If your source is already password-protected, run it through Unlock PDF first (you'll need the existing password), then add the new one here. This is also how you change a PDF's password.
"Something went wrong" on a broken file. A corrupt or non-standard PDF can fail to load; try opening and re-saving it in a normal PDF reader first, then protect the fresh copy.
Password strength still matters. The encryption is only as strong as the secret you choose — a short or common password can be guessed or brute-forced offline. Use a long, unique passphrase for anything genuinely sensitive.

Privacy

Everything — reading the PDF, encrypting it, and building the download — happens inside your browser tab. Neither the file nor the password is ever transmitted to a server, which is exactly what you want for documents you're protecting precisely because they're private.

Frequently asked questions

I forgot the password — can it be recovered?: No. The password is real encryption applied locally, and nothing about your file or password ever left your browser, so there's no reset link and no way for anyone to recover it. Write the password down somewhere safe before you send the file — this is how most people lock themselves out.
How do I change or remove a PDF's existing password?: This protect mode can't open a file that's already encrypted because it doesn't ask for a current password. Run the file through Unlock PDF first (you'll need the existing password), then add the new one here — that two-step is also how you change a password.
Does the password also block printing and copying?: The same password is set as both the user password (required to open) and the owner password (which governs permissions), so one secret controls opening the document and its printing/copying permissions together.
Why is the protected copy slightly larger than the original?: Encryption in this build is incompatible with PDF object streams, so the file is re-saved without them, which can add a bit of size. That's expected and doesn't affect how the document looks or opens.
Is the encryption strong enough for truly sensitive files?: The document is genuinely encrypted, but its security is only as strong as the password you pick — a short or common one can be guessed or brute-forced offline. Use a long, unique passphrase for anything you'd be harmed by losing.

Privacy

The password you set is applied to the PDF locally in your browser; neither the file nor the password ever reaches a server.