Aktualisiert im März 2026

Password Protect PDF — Encrypt PDF Free Online

Add a password to any PDF file for free online. Encrypt your PDF with AES-128 to prevent unauthorized access. No signup required.

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Upload a PDF to password protect it

Maximale Dateigröße 10 MB. Melden Sie sich an für mehr.

How to Password Protect a PDF Online

Add a password to your PDF in seconds to keep its contents private.

Upload Your PDF

Drag and drop your PDF file onto the upload area, or click to browse your files.

Set a Password

Enter a strong password and confirm it. This password will be required to open the PDF.

Download Protected PDF

Click "Protect PDF" and download your encrypted file. Share it securely — only people with the password can open it.

Why Choose Our PDF Protector

Strong Encryption

Your PDF is protected with industry-standard encryption to keep your data safe.

No Quality Loss

Password protection is added without re-encoding. Your PDF content remains identical.

Encrypted Upload, Auto-Delete

Your PDF is uploaded over HTTPS and automatically deleted from our server after processing. No copies are retained.

No Installation Required

Works entirely in your browser. No software to download or install.

Browser-Based, Any Device

Protect PDFs from any browser on phones, tablets, and computers without installing desktop software.

Instant Download

Your protected PDF is ready to download immediately after processing completes.

PDF Encryption FAQ

Common questions about adding passwords, encryption strength, and PDF security.

How does PDF password protection work?

Upload your PDF, choose a password, and the tool encrypts the entire file using AES-128 encryption. Anyone who wants to open the PDF will need to enter the password you set.

What encryption method is used?

Das Tool verwendet die AES-128-Verschlüsselung, den gleichen Standard, der auch von Banken und Regierungen verwendet wird. Dies bietet starken Schutz vor unbefugtem Zugriff und gewährleistet gleichzeitig eine umfassende Kompatibilität mit PDF-Readern.

Can I password-protect a PDF that already has a password?

You'll need to unlock the PDF first using our Unlock PDF tool, then re-protect it with a new password.

Will password protection change the PDF content?

No. The tool only adds an encryption layer. All text, images, fonts, annotations, and formatting remain exactly the same. The file size may increase slightly due to the encryption overhead.

What happens if I forget the password?

Es gibt keine Möglichkeit, ein vergessenes Passwort wiederherzustellen. Stellen Sie sicher, dass Sie Ihr Passwort an einem sicheren Ort wie einem Passwort-Manager speichern. Ohne das Passwort kann das PDF nicht geöffnet werden.

Ist mein PDF während der Verarbeitung sicher?

Yes. Your file is uploaded over encrypted HTTPS, encrypted on our servers, and deleted immediately after you download the result. We never store your documents or passwords.

Can I set different permissions (print, copy, edit)?

Currently the tool sets a user password required to open the PDF. All permissions are granted once the correct password is entered.

Funktioniert das mit allen PDF-Readern?

Yes. AES-128 encrypted PDFs are supported by Adobe Acrobat, Chrome, Firefox, Safari, Preview, and virtually every modern PDF reader.