Simple Online Solution for Protecting PDF Files

Improve your data security by password protecting any PDF document online.
Drag & Drop the File(s) Here
Choose File

How It Works?

Choose a PDF File

Protect any of your PDF documents in a few clicks. Select a PDF from your computer or cloud storage or just drag and drop a file into the box above.

Easily Encrypt a PDF online

Password-protect your PDFs and prevent them from unauthorized access. Only trusted recipients will be able to open and edit your documents.

Protect PDFs in the Cloud

Encrypt PDFs without downloading any additional software to your computer or phone. Save time and protect your documents online.

Absolutely Free

Forget about expensive software and time-consuming installations. AltoProtectPDF allows you to protect your PDFs absolutely for free.

Keep Your Data Secure

AltoProtectPDF keeps your documents private. All the files are securely uploaded and processed. Once you’ve downloaded your PDF, it is deleted from our server.

Encrypt PDFs on Any Device

Our app is compatible with all major operating systems like Windows, Mac OS and Linux. You can easily password-protect PDFs on any Internet-connected device.


File extension .pdf
Internet media type application/pdf
Description: The Portable Document Format (PDF) is a vector-based file format introduced by Adobe Systems in 1993. It was primarily designed for opening and editing documents on various desktop and mobile devices regardless of the operating system installed. PDFs can contain both text and images. Every page of a PDF file has a fixed layout and retains its structure when shared, printed, or downloaded to another device.
Technical Details: A PDF is a 7-bit ASCII file. It is based on the PostScript language and contains the description of a flat document with a fixed layout and all the embedded elements, such as graphic objects and fonts (in case the file includes text sections). PDF documents may also contain fillable fields, as well as interactive elements, i.e. hyperlinks, bookmarks, buttons, etc.
Developed by ISO
Initial Release: 15 June 1993
Useful links:


Customer Reviews

In terms of data security, AltoProtect is the best web-based service I know. I simply love the fact that it’s possible to password-protect any PDF directly in the web browser. Very convenient and useful!
I’ve been using AltoProtect to encrypt my PDFs for quite a long time now. And never have I had my data hacked or compromised in any way. The most reliable and safe platform I’ve seen on the Web.
See All Reviews
Rate the AltoProtectPDF

How-to guide

How to protect a PDF with a password online

  1. Open the app in your web browser.
  2. Within AltoProtect, click Choose File and browse for a file on your hard drive.
  3. Import a document from your cloud storage service (make sure pop-ups are allowed).
  4. Specify a password for your PDF. Avoid easy-to-guess sequences. Click Protect File Now!
  5. Wait while your password-protected document is being prepared for downloading (see the progress bar).
  6. Download the resulting PDF to your device or save it to your cloud storage service account.
  7. Click Work on your PDF to edit the document online (i.e. redact, sign, or share it with anybody).
  8. Click Start over again if you want to protect another PDF file.

How to Protect PDF Files from Theft

Have you been looking for a quick and convenient solution for preventing your data from unauthorized access and falling into the wrong hands? Do you want to choose which users are able to view and edit your files and which are not? With AltoProtectPDF you can protect PDF documents effortlessly. It’s a powerful and free web platform that enables you to set unique passwords for each of your PDFs. AltoProtectPDF increases the security of your information and helps you organize your workflow digitally.

Forget about paid software! There’s no longer any need to download unnecessary programs and plugins to your device. Neither will you have to worry about your space on your hard drive being used up. AltoProtectPDF enables you to use your time wisely and eliminate paper clutter once and for all. It combines both a simple, intuitive interface with a powerful toolkit accessible from any Internet-connected desktop or mobile device. It doesn’t matter if you’re a beginner or advanced user, our free online platform has been designed to suit your needs.

How to Protect a PDF Online

Using the AltoProtectPDF web application to protect PDFs from printing and copying brings you certain advantages:

  1. All the services are free of charge.
  2. No pop-up windows, harmful threats, annoying ads and banners.
  3. The highest level of security is provided.
  4. All documents are uploaded and processed via an encrypted connection.
  5. All the data is stored on an offsite server and deleted after the file has been processed.
  6. The storage space on your computer, smartphone or tablet always remains unused.

Password protect PDFs in seconds

Ensure that only trusted recipients are allowed to open and edit your documents. Follow the instructions below to password protect your PDFs against unauthorized access.

  • Drag and drop the file(s) you wish to protect into the box or press the ‘Choose File’ button to upload them from your device or cloud storage.
  • Once your document has been uploaded, type in a unique password and click ‘Protect File Now!’
  • Avoid number sequences and common words.
  • Click ‘Work on your PDF’ if you want to edit or email your file.
  • Click ‘Start over again’ if something went wrong and you wish to restart the process.
  • Press ‘Download Now’ to finish with your PDF and save it to your device.
  • Upload and encrypt as many files as you need (note that the file size should not exceed 25 Mb).

There are many other options available for your documents. Add annotations, use electronic signatures, erase or add text and so on. Enjoy unlimited storage space and keep your documents in one place. Invite your co-workers and business partners to work on the same document simultaneously. Contact the support team if you need any assistance.

AltoProtectPDF provides its customers with a plethora of up-to-date editing tools and is a fully functional digital workflow solution. It’s the best option if you’re looking for a way to quickly password-protect your PDF with impressive results. Try it today and join thousands of thankful users around the world!

Did you know?

You can send out documents to be signed

Only users who have the password can open a locked document. So it’s absolutely safe to share your docs via email. With the help of the online editing tools, you can not just format the document - but also send it for signing. Collect signatures of up to twenty people and get an email notification when the document is signed.