Password protect a PDF for free using AltoProtectPDF

Protect your PDF from being edited without having to register an account or install an application. Create and apply a password for free
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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:


How to lock a PDF quickly and securely

Review the brief guidelines below on how to password-protect a PDF for free in seconds

We deal with all sorts of PDF documents on a regular basis. Some of them might contain very sensitive information that is meant for your eyes only. If you want to make sure they do not end up in the wrong hands, you need to password-protect PDF files. You might think that your only option is to compress the file in .zip or .rar format and set a password for it, however, you can skip all the hurdles of using expensive third-party software and protect your document for free with our simple tool. Follow the steps below to quickly protect your documents online.

How to protect a PDF file with password

  1. Upload or drag and drop a PDF document. 
  2. Type in a password in to the text box. 
  3. Use hints that give feedback on the strength of your password.
  4. Click the Protect File Now button to protect the PDF with a password.
  5. Hit Download and access to the downloaded document will be password-restricted. 

Now that you know how to lock a PDF, you can be reassured that your document is hidden from prying eyes. If you want to get the most out of working with PDF files, you can continue editing your document. The whole set of features includes but not limited to authoring and editing PDFs, creating signature workflows, and annotating and converting documents. Get started today. 

Take a look at the short video guide on how to lock a PDF file

Explore the easiest way to protect PDF files with a strong password online without the need to leave your login information. Add an extra layer of security to sensitive documents in just a few clicks.

The Supreme Features Comparing Chart

Compare AltoProtectPDF to other solutions on the market for document encryption and choose the service that suits you best. To save time, just take a look at the chart below and review the features you need for better online document management and security.

View & edit
Split PDF βœ” βœ” βœ”
Merge PDF βœ” βœ” βœ”
Combine & Reorder βœ” ❌ ❌
Extract Pages βœ” ❌ ❌
Compress PDF βœ” βœ” ❌
Rotate PDF βœ” βœ” ❌
No software downloads βœ” βœ” ❌
Cloud storage Unlimited No info No info
Price Free Free 7-Day Trial paid Free 7-Day Trial paid
Encryption and security βœ” βœ” βœ”
Support 24/7/365 No info βœ”
No ads βœ” βœ” βœ”

⭐ ⭐ ⭐️ ⭐️️ ⭐️

A true salvation for me. Some documents contain sensitive data, so I have to search for a tool that could protect them. AltoProtect does everything! I can rely on it entirely.



⭐ ⭐ ⭐️ ⭐️️ ⭐️

Due to my job all of the documents I deal with contain people’s personal information that cannot be disclosed. AltoProtect handles this effortlesly. And it’s fast, reliable and free!



⭐ ⭐ ⭐️ ⭐️️ ⭐️

I highly recommend this tool for those who need data security while working with sensetive data. Creating passwords for documents is so easy now. I can make up a separate combination to protect each file. It’s great!



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How to Protect PDF Files

Add a password to your PDF to reach a higher level of document protection

How to Protect PDF Files Online

Online file passwording is one of the simplest and fastest ways to complete the operation with any internet-connected device. It a secure and highly protected way to lock the document as we use the latest data encryption and decryption methods. The solution is not overloaded with an advertisement or complicated toolkit. It is simple in use and contains detailed step-by-step instructions. The solution is easily accessible from smartphones, laptops, desktop computers and tablets, as it is fully compatible with all browsers and operating systems.

The conversion process is easily made with the following steps:

  1. Select the needed file from the cloud-based or internal storage. You may also drag and drop files. 
  2. When the document uploaded, insert a password. 
  3. Click at the Protect File Now button. 
  4. Use the Save Document as to download the final file to your device.

Being free of charge and fully compatible with all devices, connected to the internet. The solution displays perfectly on any screen or browser, making possible even on-the-go document protection and sharing. All data is removed from the service, once you start a new operation or refresh the page. Thus, be careful and always save the final file after operation finishes. This feature, in combination with anonymous document processing, makes the service fully secure and reliable. 

BackgroundHow to Protect PDF Files Online

How to Protect PDF Files With Google Chrome

Despite the wide variety of browsers developed nowadays, Google Chrome still remains one of the most frequently used and popular browsers worldwide. The reason why it is chosen by millions of people is simple in the user interface, equipped with numerous additional features. The browser supports numerous extensions for any need. The PDF lock feature is not included in clear Chrome, but available through the usage of extensions. One of the most popular among them is the Alto Protect extension for Chrome. It is the solution that helps to lock a document in several clicks.

Start with the installation of an extension. Next, follow this step-by-step instruction:

  1. Click at the extension logo at the upper right corner. 
  2. Import document from your device’s storage or Google Drive.
  3. Wait until template uploads and insert the complicated password in the corresponding field.
  4. Confirm the password to save changes. 
  5. Download the file or save it in Drive.

The combination of Chrome together with the Alto Protect extension is a perfect tool, that can substitute a polyfunctional PDF editing and management solution. The browser, equipped with all needed tools can be a perfect environment both for work and hobby. Just go to the Chrome Web application store and add enrich the browser with the needed option. Saving file to cloud storage and importing document that needs protection from saves money and accelerates the process of locking file.

BackgroundHow to Protect PDF Files With Google Chrome

How to Protect PDF Files in Windows

PDF files protection on Windows is impossible without the usage of the additional online platform or desktop app. Looking for a solution to fit your needs to pay attention to its features, interface, online or desktop type and price. According to your needs, it is possible to use the software with the fully packed toolkit or choose the option with a single lock feature. For example, you can download the software from the Microsoft store. 

Once you installed it follow steps, given below:

  1. Open file in the app.
  2. Go to security settings.
  3. Insert Password and submit changes.
  4. Save a locked file to the preferable folder. 

Be careful when selecting the software and always download drivers from the trustworthy and secure sources, like Microsoft store. It will protect you from viruses, information fraud, and system breaches. In the case of a stable internet connection, it is faster to use online-service or browser extension. If you already have pre-installed Acrobat, Word or Office 365 pack you can lock your file with it. Always create a complicated, long password with uppercase and lowercase letters. 

BackgroundHow to Protect PDF Files in Windows

How to Protect PDF Files With Preview on Mac

Mac devices have two powerful document preview, creation and editing default programs. They are Preview and Pages. Pages help to open and edit textual files and create new ones. Most people do not use the full list of features, available on Preview. It not only opens PDFs but also locks them with a custom password. The option is unavailable from the first view, but here you will know how to find it and use it to make a document protected. 

Use the following lifehack to protect your files on Mac:

  1. Open your document in Pages.
  2. Go to the print menu by clicking at CTRL+P.
  3. Click at PDF and select Save as PDF.
  4. Open Security options in the pop-up window.
  5. Add the password and click OK.

Usage of default Mac solutions and knowledge of all their features saves you time and money. There is no need to search for trustworthy online or desktop solutions, as all you need is by your hand. It has numerous features, for example, adding a signature, opening files for previewing and editing, rearranging pages, changing template format and joining several documents in one. Thus, you can just open the needed PDF in Pages and make any operation with it for free. 

BackgroundHow to Protect PDF Files With Preview on Mac

How to Protect PDF Files With Adobe Acrobat Reader

Adobe company is a pioneer of PDF processing services, as well as a founder of the format itself. Thus Adobe solutions are one of the most frequently used for editing, signing, converting, merging or locking PDF documents. It is a software that can be installed on Mac, Windows, Android or iPhone. It is available in the free trial and paid subscription modes. The trial is limited, but the lock option is available in it. Let us have a look at the document protection process with Acrobat Reader. 

Use these instructions to protect your PDF:

  1. Open file in Acrobat and choose to Protect option.
  2. Select encryption with a password.
  3. Insert the password.
  4. Submit changes and save the document.

Protection of the sensitive information is quite easy even with a trial version of Acrobat. You can control access to the files, by setting up a complicated password. This way you will be sure about the information security when sharing the file on the Internet. The first step is the installation of the service and registration in it (if you have no account yet). After that, the file passwording tool will be available. All you need is just add additional authentication to the needed file. 

BackgroundHow to Protect PDF Files With Adobe Acrobat Reader


How can One Lock a PDF without Using Acrobat?

Acrobat is a quite famous and widespread solution that contains not only editing features but lock possibility as well. But it is not the only solution for password protecting the document. This option is also available at the cloud-based Alto platform. It unlocks files easily and requires no software installation.