Runs entirely in your browser
Protect PDF with a password
Add an open password and set printing, copying, or editing permissions on your device — nothing is uploaded to a server. Drop one or more PDF files to begin.
Drag & drop PDF files here
or use the button below · multiple files supported · .pdf only
MAX 50MB PER FILE · ALREADY PASSWORD-PROTECTED PDFs ARE NOT SUPPORTED, UNLOCK FIRST
Enter a password above to enable protecting.
What Is Protect PDF?
Protecting a PDF means encrypting it so it can't be opened without a password, and optionally restricting what someone can do with it even if they do have that password — printing, copying text and images, editing, or adding comments. It's the standard way to keep a document confidential in transit or storage.
This tool reads your PDF directly in your browser, encrypts it using the same standard security handler that PDF readers like Adobe Acrobat understand, and hands back a password-protected file — all without uploading anything to a server.
Why Use Our Protect PDF Tool?
Most online protectors ask you to upload your file — and the password you want on it — to a remote server, wait in a queue, and trust that both are deleted afterward. This tool takes a different approach: reading and encrypting the PDF both happen inside your own browser tab using JavaScript. Your document and password never leave your device.
- No account or sign-up: open the page and start protecting immediately.
- No file uploads: nothing is transmitted to a server for processing.
- No paid API: encryption runs on a standard client-side implementation, not a hosted service.
- No hidden limits: protect as many PDFs as you like.
Key Features of Our Protect PDF Tool
Standard PDF encryption
Uses 128-bit RC4 encryption compatible with Adobe Acrobat 5 and later and any standards-compliant PDF reader.
Open password
Set the password required just to open and view the document.
Separate permissions password
Optionally set a second password that controls who can change the permission restrictions.
Granular permissions
Independently allow or restrict printing, copying, editing, and annotations.
Built-in verification
Every protected file is test-opened with its new password before it's handed back, to confirm the encryption worked correctly.
Batch protection
Queue up several PDFs and protect them all with the same password and permissions in one pass.
Benefits of Using Protect PDF
- Keep documents confidential: require a password before anyone can view a sensitive file.
- Stay private while protecting: in-browser processing means the password itself never touches a third-party server.
- Control reuse: stop a document from being printed, copied, or edited even by someone who has it.
- Widely compatible: the resulting file opens in Adobe Acrobat, browser PDF viewers, and most PDF software.
- No software to install: everything runs in the browser you already have open.
How to Use Protect PDF?
- Add your PDF. Drag and drop one or more PDF files onto the drop area, or click "Browse files" to select them.
- Set a password. Enter the password anyone opening the file will need. Add a separate permissions password if you'd like one.
- Choose permissions. Allow or restrict printing, copying, editing, and annotations.
- Click "Protect PDF." Each file is encrypted and verified entirely on your device.
- Download your results. Use the download button in the summary window that appears — a single PDF, or a .zip if you protected more than one.
Supported File Formats
| Format | Direction | Notes |
|---|---|---|
| PDF (.pdf) | Input | Standard, unencrypted PDF files. |
| PDF (.pdf) | Output | A password-protected PDF using 128-bit RC4 standard encryption. |
| ZIP (.zip) | Output | Automatically offered whenever more than one file is protected at once. |
Why Choose Our Online PDF Tool?
There's no shortage of PDF protectors online, but many route your file — and the password meant to guard it — through a server, require a paid plan, or limit how many files you can process per day. This tool is built around a simpler premise: encrypt entirely on your device using a standard, well-documented algorithm — no paid conversion API involved — and stay free to use without a login.
Privacy and Security
Because protection happens client-side, your PDF and the password you choose are used directly in your browser's memory and are never transmitted anywhere — at no point does the file content or password reach a server operated by this site or anyone else.
Common Use Cases
- Sending sensitive documents by email — contracts, financial statements, medical records — with a password required to open them.
- Restricting a report to view-only by disabling printing and copying while still allowing it to be read.
- Sharing a document for review while blocking edits until you approve them.
- Archiving confidential files so they can't be casually opened by anyone who comes across them.
Frequently Asked Questions
Is this Protect PDF tool really free?
Yes. There's no sign-up, no per-file fee, and no watermark added to the protected document.
Are my files or password uploaded to a server?
No. Reading and encrypting the PDF both run inside your browser using JavaScript. Neither your document nor the password you set is transmitted anywhere.
What encryption does this use?
128-bit RC4 encryption under the PDF standard security handler (revision 3), the same scheme supported by Adobe Acrobat 5 and later and virtually every PDF reader. It's not the newest AES-256 scheme found in very recent PDF software, but it's broadly compatible and still requires the correct password to open the file.
Will document metadata like the title still be readable?
The page content — text, images, and everything you actually see — is fully encrypted and requires the password to view. A small number of short metadata fields, such as the document title, are a best-effort case and may not always display correctly in every PDF reader's document properties panel.
Can it protect a PDF that's already password-protected?
No. Remove the existing password with a PDF unlock tool first, then protect the result with your new password.
What happens if I forget the password I set?
There's no way to recover it. This tool doesn't store your password anywhere, so keep a copy of it somewhere safe before you lose access to the unprotected original.
Is there a limit to how many files I can protect?
No daily limit is enforced. The practical limits are your device's memory and the 50MB-per-file size cap, which keeps in-browser processing responsive.
Conclusion
Locking down a sensitive PDF shouldn't require handing both the file and its new password to an unknown server. This tool aims to make protecting fast, private, and free — encrypting and verifying your document entirely on your own device, from a single confidential file to a full batch.