Password Protect PDF
Add a password to any PDF so it can only be opened by people who have it. Fast, private, and completely free.
Click or drag and drop a PDF file
One PDF at a time. Your file never leaves your browser.
Why Flip Caps
Lock your documents in seconds
Real AES Encryption
Your PDF is encrypted with the standard PDF security handler, the same scheme business document tools use. The password is genuinely required to open the file.
100% Private
Your PDF and password never leave your browser. All encryption happens locally with JavaScript, so nothing is uploaded to any server.
Set Permissions
Beyond a password to open, you can block printing, copying text, and editing for anyone who opens the document.
Instant and Free
Protect a document in seconds with no account, no sign-up, and no watermark added to your file.
Works Everywhere
The protected PDF opens in Acrobat, Preview, Chrome, Edge, and every standard PDF reader on desktop and mobile.
Works on Mobile
Protect a PDF straight from your phone or tablet. No desktop software to install.
How It Works
Three steps to a protected PDF
Upload Your PDF
Click the upload area or drag a PDF onto the page. The file is loaded into your browser only, never sent anywhere.
Set a Password
Type the password you want, confirm it, and optionally choose which actions to allow once the file is opened.
Download
Click Protect PDF and download your encrypted file. From now on it asks for the password every time it is opened.
Frequently Asked Questions
Is the password protection real encryption?
Yes. The file is encrypted using the standard PDF security handler. Without the password the content cannot be read, and every compliant PDF reader will prompt for the password before opening it.
Are my PDF and password uploaded to a server?
No. Everything happens in your browser using JavaScript. Your document and the password you choose are never sent to any server, so the process is completely private.
What happens if I forget the password?
There is no way to recover it. The password is not stored anywhere, so keep your original unprotected file as a backup in a safe place before you protect it.
Can I stop people from printing or copying my PDF?
Yes. Open the permissions options and untick printing, copying, or editing. Those actions are then blocked for anyone who opens the file with the password.
Will the protected PDF open on phones and other apps?
Yes. The protected file follows the standard PDF format, so it opens in Acrobat, Apple Preview, Chrome, Edge, and mobile PDF apps. Each will ask for the password.
Can I protect a PDF that already has a password?
Not directly. You would need to open it with its current password and remove that first, then protect it again with a new password.
About Password Protect PDF
The Flip Caps Password Protect PDF tool encrypts any PDF directly in your browser, so a password is required before the document can be opened. It is ideal for contracts, invoices, statements, medical records, and anything else you want to share securely.
The encryption runs entirely client side, which means your file and your password are never uploaded. You can also restrict printing, copying, and editing, giving you control over what a reader can do once the file is open.
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