Password Protect PDF Online
Lock your PDF with AES-256 encryption. Add an open password and, if you want, restrict printing, copying, or editing — free, no sign-up required.
Drag & drop your PDF here
or click to browse from your computer
Max 100MB per upload
Set a password to open this PDF
Password strength: —
Passwords don't match.
Permissions (applied once the file is opened)
Encryption strength
Someone who knows only the owner password (not the open password) can override the permissions above.
Preparing...
Your PDF is now password protected
Keep your password somewhere safe — if you lose it, the file can't be recovered.
AES-256 encryption
Applied to your PDF's contents, with AES-128 available for older readers.
Fine-grained control
Optionally restrict printing, copying, editing, or form filling — independent of the open password.
Completely free
Protect your PDFs up to 100MB, with no sign-up required.
How to Password Protect a PDF
- Upload your PDF. Drag it in or click to browse. Files up to 100MB.
- Enter a password. This is what someone will need to open the file.
- Choose what to restrict, if anything. By default, printing, copying, editing, and form-filling stay allowed for anyone who has the password — turn off whichever you want to prevent.
- Pick your encryption strength. AES-256 is selected by default; AES-128 is available for compatibility with older PDF readers.
- Click Protect. Your file is encrypted on our server and never written to disk.
- Download your protected PDF.
What's the Difference Between a Password and Permissions?
This trips up more people than any other part of PDF protection, so it's worth being precise about.
The password you set controls whether someone can open the file at all. Without it, the PDF simply won't open in a compliant PDF reader.
Permissions — printing, copying, editing, form-filling — are a separate layer. They apply after the file is opened with that password. You can optionally set a second, different password (an "owner password") that only someone changing those permissions would need — the person just reading the file never sees it.
One thing worth knowing honestly: permission restrictions are a standard built into the PDF format that compliant software respects — they're not a cryptographic lock on printing or copying the way the open password is a lock on opening the file. A reader that doesn't follow the PDF permissions standard can, in principle, ignore them. Most mainstream PDF software does respect them, but if you need an absolute guarantee that content can never be extracted or printed, permissions alone aren't that guarantee — the password requirement to open the file is the strong part of the protection.
Choosing What to Restrict
Four restrictions are available, independently:
- Printing — stop the file from being printed
- Copying — stop text and images from being extracted or copied
- Editing — stop the document's content from being modified
- Forms & annotations — stop form fields from being filled in or comments from being added
All four are allowed by default — you only need to touch the ones you actually want to restrict.
Why Password Protect a PDF?
Some documents are only meant for one recipient, or shouldn't be readable if they end up in the wrong inbox — contracts, invoices, financial statements, employee records, academic transcripts, legal documents, anything with a client's personal details. A password doesn't replace judgment about who you send a file to, but it does mean a document that's accidentally forwarded, left on a shared drive, or intercepted isn't immediately readable by whoever finds it.
Choosing a Strong Password
- Use something long — short passwords are easier to guess or brute-force than most people expect.
- Avoid anything tied to public information about you or your document (names, dates, company names).
- Don't reuse a password you use for anything else, especially for sensitive documents.
- Send the password to your recipient through a different channel than the file itself — a text message, not the same email.
- Write it down somewhere secure if you need to. There's no way to recover or reset a forgotten PDF password — not from CurePDF, not from any tool, since the password is what the encryption is built on.
Protect PDF Online vs. Desktop Software
An online tool makes sense for a one-off document you need protected right now — no installation, works from any device with a browser, and you're done in the time it'd take to open a desktop app. Desktop software still has its place if you're protecting PDFs constantly as part of a workflow, or need features beyond what a browser tool offers. For most people protecting a document occasionally, the browser is the faster path.
Is It Safe to Protect a PDF Online?
Your file and the password you set are sent to our server to apply the encryption — this tool doesn't run entirely in your browser the way some of CurePDF's other tools do for smaller files. The file is processed in memory and never written to disk. Per CurePDF's Privacy Policy, uploads are automatically deleted within 1 hour, and file contents aren't reviewed or shared. As with any online tool, avoid uploading documents with extremely sensitive information, like full financial account numbers or government ID numbers, unless you're comfortable with standard web-based processing.
Frequently Asked Questions
How do I password protect a PDF?
Upload your file, set a password, choose any restrictions you want, and click Protect.
Can I protect a PDF online for free?
Yes, with no account required.
Can I password protect a PDF without Adobe Acrobat?
Yes — CurePDF's protect tool works independently in your browser.
How do I lock a PDF from editing?
Turn off the Editing permission when protecting the file — the open password stays required, and editing is additionally restricted.
Can I prevent someone from copying text from a PDF?
You can turn off the Copying permission. As with any PDF permission restriction, this is respected by compliant PDF software but isn't an absolute technical guarantee against every possible way of extracting text.
Can I prevent printing of a PDF?
Yes, by turning off the Printing permission the same way.
Is password-protecting a PDF secure?
The open password is enforced by AES-256 or AES-128 encryption, a real cryptographic barrier to opening the file. Permission restrictions like print or copy are a separate, weaker layer respected by compliant software rather than a cryptographic lock.
Can I protect a PDF on my phone?
Yes, it works the same in a mobile browser as on desktop.
Can I password protect a large PDF?
Yes, up to 100MB.
What happens if I forget my PDF password?
There's no way to recover it, from CurePDF or any other tool. Keep it somewhere safe when you set it.
Can I remove a password from a PDF?
Not currently — CurePDF doesn't have a password-removal tool.
What's the difference between the password and the permissions I can set?
The password controls whether the file opens at all. Permissions like printing, copying, editing, and forms are a separate setting that applies once the file is already open.
What encryption does CurePDF use?
AES-256 by default, with AES-128 available for compatibility with older PDF readers.