The short answer
Type the password in the Password field of the tool below and repeat it in Repeat password. Then drop one or more PDF files. As soon as both fields match, each file is encrypted and gets a Download button; several files can be downloaded together as a ZIP. Use Show to check what you typed before you share the file.
By default the PDF is encrypted with AES-256 and every action stays allowed once the file is open. If you also want to stop printing, copying or editing, untick those boxes under Allow. You do not need Adobe Acrobat or any installed program, and it works the same on Windows, Mac, iPhone and Android.
Try it here: Protect PDF
Open the full tool pageOpen password and permissions password
A PDF can have two passwords, and they do very different jobs. Knowing the difference avoids the most common mistake, which is to think a file is locked when it is not.
- Open password (user password): the file cannot be opened without it. Its pages, text and images are stored encrypted, so even someone who looks at the raw file sees only scrambled data. This is the real protection.
- Permissions password (owner password): it controls what readers allow once the file is open, such as printing, copying text and images, or editing and adding comments. Without an open password, anyone can still read the document.
- In this tool the open password is always required. The permissions password field appears only when you untick one of the actions under Allow. If you leave it empty, a long random one is used, which means the limits cannot be lifted later.
AES-256 or AES-128
Both are strong, standard encryption methods. AES-256 is the method of the current PDF standard and the right choice in almost every case. AES-128 exists for compatibility with very old PDF readers from before 2008. Older PDF tools also used a method called RC4, which is no longer considered safe; this tool does not create RC4 files.
| AES-256 (default) | AES-128 | |
|---|---|---|
| Opens in Adobe Acrobat and Reader | Version 9 and later | Version 7 and later |
| Chrome, Edge, Firefox, Safari | Yes | Yes |
| iPhone, iPad and Android | Yes | Yes |
| Password characters | Any letters, including accents and other alphabets | Latin letters, numbers and common symbols |
| When to choose | Always, unless a very old reader must open it | Only for very old PDF software |
Choosing a password that actually protects
Encryption only works as well as the password behind it. Short or common passwords can be guessed by programs that try millions of combinations, while long ones are out of reach. A few rules make the difference.
- Length beats complexity: four random words or a sentence of 12 or more characters is stronger than a short mix like Pa55!.
- Do not reuse the password of your email, bank or work account. If the PDF password leaks, nothing else should be exposed.
- Avoid things others can find, such as a birthday, a phone number or the company name.
- Store it somewhere safe, like a password manager. Nobody can recover a forgotten PDF password, including us, so keep the unprotected original too.
- For files sent to many people, use a password made for that file only, so you can share it without exposing anything else.
Sharing a protected PDF safely
The most common way protection fails is the password travelling with the file. If the PDF and the password are in the same email, anyone who gets that email gets both. Send the file by email or a file sharing link, and the password another way: a phone call, a text message, a chat app or in person.
For a document you send regularly to the same person, agree on a rule once, for example the last digits of their customer number plus a word you both know. Tell the recipient that capital letters matter and that the password must be typed exactly. Many support calls come from a capital letter or a space added by copy and paste.
What printing and copying limits really do
The limits are stored inside the encrypted file and most PDF apps respect them: Adobe Reader, browser viewers and phone apps hide or grey out printing or copying when they are not allowed. They are useful to signal how a document may be used and to stop accidental printing or copying.
They are not a strong barrier. Anyone who can open the file can read and photograph it, and some programs ignore the limits. If a document must not be read by the wrong person, the open password is what protects it. If you want a printed or copied version to show where it came from, add a watermark with the recipient's name before you protect the file.
Common problems and fixes
- The file is not processed and says to type a password: both password fields must be filled in and match. Use Show to compare them.
- AES-128 rejects the password: some letters, such as letters from non Latin alphabets, cannot be stored with AES-128. Choose AES-256 or change the password.
- The PDF already has a password: remove it first with Unlock PDF, using the password you know, then protect the unlocked copy again. Files that only limit printing or copying are handled automatically and get your new settings.
- The protected file is a bit larger than the original: the tool writes each part of the PDF separately so that it can be encrypted. The difference is usually small.
- The recipient cannot open the file: check that they use a current PDF app, and that they type the password with the same capital letters.