How to protect a PDF file

After having caught your brother sticking his nose into your documents, you have decided to protect the PDF files on your computer with a password, but unfortunately, you don’t have the slightest idea how to do it and, above all, which tools to use. Don’t worry, I can help you out. Give me just a few minutes of your time and I will explain, in no time, how to succeed in your intent.

I already anticipate that, to protect a PDF file, you can choose to rely on “classic” PC programs, special online services or, from mobile, applications for smartphones and tablets. In all cases, however, you have absolutely nothing to worry about: the procedure to be implemented is definitely much simpler than you might think.

Then? May I know what are you still standing there? Position yourself comfortably, take some free time just for yourself and immediately start focusing on reading what is written below. I am sure that, in the end, you will be able to tell yourself very happy and satisfied with what you have learned and that you will also be ready to say that in reality it was a real child’s play. What do you say, we bet?


  • How to protect a PDF file on a computer
    • LibreOffice (Windows / macOS / Linux)
    • Adobe Acrobat Pro (Windows / macOS)
    • Preview (macOS)
  • How to protect a PDF file online
    • PDF2GO
    • PDFCandy
  • How to protect a PDF file on smartphones and tablets

How to protect a PDF file on a computer

Are you interested in understanding how to protect a PDF file from a computer? Then rely on the software solutions that I have indicated and explained to you below.

LibreOffice (Windows / macOS / Linux)

The first program to protect PDF files that I want to invite you to consider is LibreOffice: it is a free and open-source office suite running on Windows, macOS and Linux. It is especially popular with those looking for an alternative to Microsoft Office. It allows you to view, edit and create text documents, spreadsheets etc. making available to users all the necessary tools and functions. It also allows you to open and edit PDF files and, obviously, to intervene on the security settings of the latter.

To use it, go to the suite’s website and press the Download the xxx version button. to download the software. When the download is complete, if you are using Windows, open the .msi file obtained and, in the window that appears, press the Run button. Then click on the Next button, select the Typical option and press the Next and Install buttons. To conclude the setup, click on the Yes and Finish buttons.

If you are using macOS, open the .dmg package obtained, drag the LibreOffice icon into the Applications folder, right-click on it and select the Open item from the menu that appears. Then click on the Open button in the notice that is proposed to you, so as to start the program by going around the limitations imposed by Apple on applications from non-certified developers (an operation that must be carried out only at the first start).

Subsequently, still on macOS, go back to the LibreOffice website and press the Translated user interface button, in order to pick up the Italian translation of the suite. When the download is complete, close LibreOffice (by pressing cmd + q  on the keyboard), open the .dmg package you just obtained, right-click on the LibreOffice Language Pack executable contained within it,   select the Open item from the menu that appears and press the Open buttons and Install. Then, select the entry / Applications / from the window that opens and click the Install button. If a warning appears referring to permissions, press the Yes button, identify me, type the password of your user account on macOS and click the OK button twice in a row.

Therefore, open the PDF in relation to which you want to go to act, by clicking on the Open file button located in the upper left part of the LibreOffice home screen and, once the import is complete, go to the File menu > Export to PDF format  ( top left).

In the new window that appears, go to the Security tab and click the Set password button, then type the authorization password and the opening password (in the appropriate fields) and click the OK button. Then adjust the options related to document protection by selecting the ones you prefer on the left, press the Export button and specify the location on your computer where you want to save the protected PDF. Done!

Adobe Acrobat Pro (Windows / macOS)

Another useful tool for this purpose that I want to point out is Adobe Acrobat Pro, the renowned software from Adobe thanks to which it is possible to view, edit, convert and protect documents in PDF format in a complete and professional way. It is available for both Windows and macOS and is paid (has a base price of 18.29 euros/month), but you can use it in a free trial version that works without limits for 7 days.

To download the Adobe Acrobat Pro trial on your PC, go to the program’s website and click on the Activate trial version and Go buttons. Then enter your email address in the appropriate field and follow the wizard that is proposed to you to create an Adobe ID and start the trial period. If, on the other hand, you already have an Adobe account, you will be prompted to enter the relevant password to log in. Once these preliminary procedures have been completed, the software installation file will then be downloaded.

When the download is complete, if you are using Windows, start the .exe file obtained and, in the window that opens, click on the Yes button. In the new screen that appears, log in with the Adobe account you just created, indicate your proficiency level in using Acrobat Pro, click on the Start installing button and wait for the process to complete.

If, on the other hand, you are using macOS, open the .dmg package obtained, right-click on the program installer present in it and select the Open item from the contextual menu displayed, in order to start the software, however, going around the limitations imposed from Apple to non-certified developers (operation that must be performed only at the first start). Next, type in the password of your user account on macOS and hit the OK button. Next, log in with your Adobe account and wait for the software installation procedure to complete.

Now that, regardless of the operating system used, you see the main Adobe Acrobat Pro screen, open the PDF you want to protect, by clicking on the File menu (top left) and on the Open item contained in it, then select the Protection item in the right sidebar and, in the toolbar at the top, click on the  More options and Protection properties options.

In the screen you now see, select the Password protection option from the Security method menu, check the Restrict printing and editing of the document box and set the None option in Changes allowed.

Finally, type the password you want to use to protect the PDF in the field adjacent to the Change password for permissions item and click the OK button. Then type the password again and click the OK button twice in a row. Then click on the floppy disk icon that you find in the upper left part of the window and the protected PDF will be saved on your computer.

Preview (macOS)

Are you using a Mac? If so, I’m happy to inform you that you don’t necessarily need to use third-party tools to secure your PDF files. In fact, you can do everything directly and comfortably with Preview, the application already included in macOS to view/edit images and, in fact, PDF documents.

You ask me how to make use of it? I’ll explain it to you right away. First, open the PDF document you are interested in going to act on, simply by double-clicking on its icon. If Preview is not set as the default program for opening the aforementioned file type, right-click on the icon of the PDF file to be protected and select the items Open with> Preview from the context menu.

Once the PDF is open, press the File menu located at the top left and select the Print item from the latter. Then click on the PDF drop-down menu  (located at the bottom left) and select the Save as PDF option. In the screen that is shown to you at this point, press the Security Options button and select the security options you prefer between Request password to open the documentRequest password to copy text, images and other content and Request password to print the document.

Then type the password you want to use in the relevant fields below and click on the OK button. Finally, click on the Save button to save your PDF with a password.

How to protect a PDF file online

Now let’s see how to protect a PDF file online, using the appropriate services. If this interests you, below you will find those that, in my humble opinion, represent the best solutions in the category: try them now!


The first of the online solutions that I want to recommend is  PDF2GO: it is a totally free web service, easy to use and which integrates a special function thanks to which it is possible to protect PDF documents with a password. Note that all files uploaded to the service are automatically deleted after 24 hours.

To use it, connect to the PDF2GO website and drag the document you want to act on into the browser window. Alternatively, you can select the document manually by clicking the Choose file button.

And if your file is on one of the supported cloud storage services, such as Google Drive and Dropbox, click on the relevant icon, log in to your account and download them from there. You can also upload a file from any other online location by pressing the Enter URL button and typing the relevant link.

Once uploaded, if you only want to set a password for opening the document, fill in the fields below the words  Set password to open the document with the keyword you want to use and continue reading the next paragraph. If, on the other hand, you want to use a password to also restrict printing, copying and/or editing, choose the options you prefer from the Settings section  (below) and type the password you want to use in the appropriate fields below.

Finally, click on the  Save changes button and that’s it: later, you can download the document to which the protection has been applied to your computer simply by pressing the Download button. Alternatively, you can press the Download ZIP file button, to download a ZIP archive containing the PDF file, or click the button with a speech bubble icon to upload the document to a cloud storage service, such as Dropbox or Google Drive.


As an alternative to the online service I have already told you about, I suggest you consider PDFCandy: it is another Web solution that provides users with various tools for editing PDFs, including one suitable for protecting documents. from the opening and the press. It is free, very easy to use and, moreover, it protects users’ privacy by deleting the files uploaded to its servers within a few hours.

To use it, go to the PDFCandy website and drag the PDF you want to act on in the browser window. If you prefer, you can “manually” select the document by clicking the Add File button in the center of the page. Alternatively, if the document is online, on  Google Drive or Dropbox, you can also take it directly from there, by clicking on the relevant service icon and logging into your account.

At this point, type the password you want to use to protect the document in the Password and Reset fields (below) and click on the Protect adjacent PDF button. Then download the PDF obtained by clicking on the Download file button or, if you want to save it on one of the supported cloud storage services, click on the relative icons.

How to protect a PDF file on smartphones and tablets

As anticipated at the beginning of the article, protecting a PDF file is also feasible from a smartphone or tablet: just use the right apps. Among the various solutions available on the market, I recommend  Foxit MobilePDF which is free and works on both Android and iOS. It allows you to view and modify the type of documents in question but also to add a password for opening, editing and printing PDFs. It should be noted that the aforementioned functions are paid and must be unlocked through in-app purchases (at a cost of 10.99 euros/year). However, you can take advantage of the 7-day free trial period to evaluate all its features.

To download Foxit MobilePDF on Android, connect to the relevant section of the Play Store and press the Install button. To download it on iOS, visit the relevant section of the App Store, press the Get / Install button and authorize the download via Face IDTouch ID or password. Then, start the app by pressing on its icon added to the home screen.

At this point, perform a series of swipes from right to left to scroll through the initial presentation of the app and press the Start button. Then press the button with the three lines horizontally located at the top left and select the items Documents or Recent from the menu that opens, to select a PDF file in the device memory.

Now, press the button with the three vertical dots at the top right, select the Protect by password option (on Android) or the File encryption option (on iOS) and activate the trial version of the app to take advantage of the aforementioned functionality.

Finally, activate the Add document restrictions option and decide which options to keep enabled and which to disable. Finally, scroll down the screen, type the password you want to use in the Password field  and press the confirmation button. As proof of the success of the operation, you will see a special message appear on the screen.


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