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Protect PDF

Local

Add password protection to PDF

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Protect PDF
Local
Tool Details
Input formatsPDF
Output formatPDF
Max file size100 MB
Max files1
ProcessingLocal
Related Tools

Unlock PDF

Remove printing, copying and editing restrictions from a PDF

Privacy First

Your files are processed entirely in your browser. Nothing is uploaded to any server.

How do I password protect a PDF?

Add your PDF, set a password, then protect and download the encrypted file. Opening it afterwards requires the password in any standards-compliant PDF reader. The encryption is performed by this browser tab — your document and your password are never transmitted, which is what makes local processing essential for this particular tool.

About the Protect PDF

Add password protection to PDF files. Set a password required to open the document.

  • Put a password on a payslip, medical letter or contract before attaching it to an email that will sit in a shared inbox.
  • Add a document-open password to files stored on a USB stick, a shared drive or a laptop that travels.
  • Set the password locally, so the secret is typed into your own browser and never transmitted to a server that could log it.
  • Confirm the password twice before encrypting, so a typo does not lock you out of your own file.

How to use the Protect PDF tool

  1. 1

    Upload PDF file

    Select PDF file from your device or drag file into the upload area.

  2. 2

    Choose settings

    Choose settings such as Set Password, Confirm Password before processing.

  3. 3

    Protect PDF

    Run the Protect PDF tool to create the PDF output.

  4. 4

    Download the result

    Download the finished file. The original file stays on your device and is not uploaded.

What encryption does the tool apply?

AES encryption, applied through a pdf-lib fork that supports it. The document header is upgraded before encrypting so that older PDFs do not cause a silent fallback to obsolete RC4, which is broken and trivially stripped by free tools. The password you set is applied as both the user password, required to open the file, and the owner password, which governs permissions.

Why does uploading a file to encrypt it defeat the point?

Because encryption is the one operation where the tool must handle both the confidential document and the password protecting it. A web service that encrypts server-side necessarily receives the plaintext file and the key together, so for the duration of that request your protection is worth nothing and depends entirely on the operator's conduct and retention policy. Doing it in the browser removes that window: neither the file nor the password crosses the network.

What happens if you forget the password?

The document is unrecoverable, and that is by design rather than a limitation to work around. There is no reset, no backdoor, and no recovery path — properly implemented AES encryption offers none. Store the password in a password manager before you send the file, and send it to the recipient through a different channel than the document itself.

Are my files uploaded when password protecting a PDF?

No. This is the tool where that answer matters most. The file is encrypted in memory in this tab and saved directly to a download, so the unprotected original and the password exist only on your machine. Encrypting a sensitive document by first uploading it to a stranger's server is a contradiction, and it is the standard model for most free online alternatives.

How to do this offline, on the command line

qpdf can apply AES-256 encryption and set the individual permission bits.

qpdf

macOS: brew install qpdf · Debian/Ubuntu: apt install qpdf

qpdf --encrypt USERPASS OWNERPASS 256 -- payslip.pdf protected.pdf

Leave the user password empty ("") to allow opening while still restricting printing and extraction with --print=none --extract=n.

Frequently Asked Questions

How does the password protection work?
Your PDF is encrypted in the browser with standard PDF encryption. Anyone opening the file afterwards — in Adobe Acrobat, Preview, a browser, or a phone — must enter the password you set.
Is it safe to add a password to a PDF online?
With PDFBase, yes: the file and the password never leave your device because encryption runs locally in your browser. Most online protectors upload your document to a server first, which defeats the purpose of protecting it.
What happens if I forget the password?
There is no back door — the encryption is real, and neither PDFBase nor anyone else can recover the contents without the password. Store it in a password manager and keep an unprotected copy somewhere safe.
Which documents should I password-protect?
Anything you would not want read if the file were forwarded or a device were lost: contracts, payslips, financial statements, medical records, and identity documents.

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