peartools

Password Protect PDF

Add a password to a PDF so it will not open without it. You can also add a second password that holds back printing, copying, and editing. The file is encrypted with AES-256 inside your browser, and neither the document nor the password is ever uploaded.

Drag and drop your PDF here, or

Up to 100 MB. The password is applied in your browser. Nothing is uploaded.

What PDF password protection does

Protecting a PDF encrypts it. The text, the images, and the fonts are all scrambled inside the file, and the key that turns them back into a readable page is worked out from the password you set. No password, no key, no document.

This is not the same as hiding a file, marking it confidential, or zipping it. Those rely on people behaving. Encryption does not: a reader that does not have the password has nothing to display, and the words are not sitting in the file waiting to be found.

The password travels separately from the file, which is the part people miss. Emailing the locked PDF and the password in the same message protects nothing at all. Send the password by text, by phone, or through a password manager instead.

Why use our PDF password protection

  • ·Nothing is uploaded. The file you are locking is the last one you should send to somebody else's server. This one never leaves your tab.
  • ·AES-256 by default. The strongest option the PDF standard defines, not the old RC4 that some tools still write.
  • ·Both kinds of password. Lock the file shut, limit what readers can do, or do both. Most free tools only offer the first.
  • ·The document is untouched. Pages, text, images, and form fields come out exactly as they went in. Only the encryption is added.
  • ·Free. No signup, no page limit, and no watermark on the result.

Open password vs permissions password

A PDF can carry two passwords, and they are not two strengths of the same thing. They do completely different jobs, which is why a file can refuse to open for one person and print fine for another.

The open password is the one everybody pictures. The reader asks for it before it will show you anything, and without it there is no document to look at. The PDF standard calls this the user password. It is the one to use for a payslip, a bank statement, or a contract.

The permissions password works the other way round. Anyone can open the file and read it, but the document carries a list of what readers are allowed to do with it: print, copy text, edit, add comments, fill in the form, add or remove pages. Whoever knows this password gets past that list. The standard calls it the owner password.

The important limit is that the second one asks a reader to behave rather than making it impossible to misbehave. The content is still decrypted on screen, so the reader could ignore the list if it wanted to. Mainstream readers do not, and greying out the print button stops the ordinary accidental copy. But if the content genuinely must not get out, an open password is the one that does that work.

One trap worth knowing: if you set both passwords to the same thing, the limits stop meaning anything, because everyone who can open the file is also holding the password that overrides the restrictions. When you turn on limits here, the tool asks for a different password for exactly that reason.

How to password protect a PDF

  1. 1

    Add your PDF

    Drag the file onto the box or click to pick it. It stays in your browser, which matters here more than anywhere: a document worth locking is not one to hand to a server first.

  2. 2

    Type the password twice

    The second box catches a typo before it becomes a file nobody can open. There is no reset link for a PDF password, so this step is worth the extra three seconds.

  3. 3

    Choose whether to limit printing or copying

    Leave this off and the password simply opens the file. Turn it on to add a second password that holds back printing, copying, or editing for everyone else.

  4. 4

    Download the protected PDF

    The file is encrypted with AES-256 and saved to your device. Open it once to check the password before you send it on.

How strong PDF encryption is

PDFs have been encrypted in several different ways over the years, and they are not equally good. The oldest, RC4 with a 40-bit key, dates from the 1990s and can be broken by an ordinary computer in a short time regardless of how good the password is. RC4 with 128 bits is better but still built on a cipher nobody recommends any more. Some free tools still write these.

AES-128 arrived with Acrobat 7 and is genuinely strong. AES-256, from Acrobat X in 2010, is the only one the current PDF standard still recommends, and it is what this tool uses unless you choose otherwise. There is no known way to read an AES-256 PDF without the password.

Which moves the whole question onto the password. The encryption key is worked out from what you type, so a file locked with1234 is not protected by AES-256 in any meaningful sense: software can try every short password in order, and it will find that one almost immediately. Length is what defeats that, far more than mixing in symbols. Four unrelated words you can actually remember beat eight clever characters you cannot.

The other half of the job is where the password goes. Put it in a password manager, or send it through a different channel from the file, and keep an unprotected original somewhere safe in case the password is lost.

Who password protects PDFs

Anyone sending a document that would matter if it reached the wrong person. These are the most common cases:

  • ·Anyone emailing a payslip, invoice, or statement. Email gets forwarded, and mailboxes get shared. A password means the file is only readable by the person you gave the password to, not everyone the message reaches.
  • ·Accountants and bookkeepers. Tax returns, year end accounts, and payroll summaries go out by email every day. Locking the file is the quickest way to keep a misdirected message from becoming a real problem.
  • ·HR teams sending contracts and offers. Salary, address, and start date sit in the same document. A password keeps it between you and the person it belongs to.
  • ·Anyone sharing a document that must not be edited. A permissions password lets people read and print a price list, a policy, or a quote while holding back copying and editing in most readers.

A password stops people opening the file. It does not remove anything from inside it, so if the document itself says more than the recipient should see, redact the PDF first and clear the file details with our PDF metadata remover. When you need the password taken off again, our unlock PDF tool removes it from a file you can already open.

Frequently asked questions

How do I password protect a PDF for free?
Add your PDF, type a password twice, and download. The file is encrypted in your browser with AES-256 and the copy you get will not open without that password. There is no signup, no watermark, and nothing is uploaded.
Can I password protect a PDF without Acrobat?
Yes. This tool does the same job in a browser tab, with no software to install and no account. The result is an ordinary encrypted PDF, so Acrobat, Preview, Chrome, Edge, and the PDF apps on Android and iOS all ask for the password and open it normally.
What is the difference between an open password and a permissions password?
An open password stops the file opening at all: no password, no document. A permissions password lets anyone open and read the file, but tells readers to hold back printing, copying, or editing unless that second password is given. They do different jobs and you can use one, the other, or both.
Can I stop people printing or copying a PDF?
Yes, by setting a permissions password and unticking what you want held back. Be clear on what that gives you: the limits are an instruction to the PDF reader, and mainstream readers follow them, but the content is not locked away the way it is behind an open password. If it truly must not be copied, use an open password as well.
What happens if I forget the PDF password?
The file cannot be opened. There is no reset, no recovery, and nothing we can do to help, because the password is never sent to us and the encryption key is derived from it. Keep the password in a password manager, and keep the original unprotected file somewhere safe.
Is a password protected PDF actually secure?
With AES-256 and a long password, yes. The encryption is the same standard used to protect files elsewhere and there is no shortcut through it. The weak point is almost always the password itself. A short or obvious one can be guessed by software that tries millions of options, so length is what matters most.
Will the password work on a phone?
Yes. AES-256 encryption has been supported since Acrobat X in 2010 and works in current versions of iOS, Android, macOS Preview, Chrome, and Edge. If you need to support something much older, switch the encryption setting to AES-128.
Does adding a password change the pages or the file size?
No. The pages, text, images, and form fields are exactly as they were. The file grows by a few hundred bytes for the encryption details, and that is all.
Are my PDF files private?
Yes. The file is opened, encrypted, and saved inside your browser tab. Neither the PDF nor the password is ever uploaded to a server, and once the page has loaded the tool keeps working offline.

We never see your password, so we can never recover it. Save it somewhere before you send the file.