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 extra protection to the documents with sensitive data using our online solution. Password protect your docs unlimitedly from the smartphone or computer.

How to password protect PDFs online

If you’re looking for the fastest way to protect your PDFs for free, our online solution comes in handy. AltoProtectPDF allows you to apply encryption regardless of your device. Using a strong internet connection, protect your PDFs from being edited without your consent. 

Take a look at our step-by-step instructions on how to password protect PDFs online:

  1. Go to AltoPasswordPDF via your preferred browser.
  2. Click Choose File or upload a document from your device or cloud storage.
  3. Create a password and enter it.
  4. Click Protect File Now! to save the changes.
  5. Download the encrypted PDF or send it out.

You can upload and protect as many documents as you want. Plus, AltoProtectPDF provides you with the most reliable third-party-prevention methods. Once you’ve protected and downloaded your PDF, it’s deleted from our server. Lock and share your documents, knowing that all your data is secure and well-protected. Try it out now and say goodbye to expensive apps and time consuming steps.

BackgroundHow to password protect PDFs online

How to password protect PDFs via Chrome

Enhance Chrome by implementing a free and easy-to-use online encryption solution. Take advantage of a Chrome add-on that allows you to password-protect PDFs. Add the AltoProtectPDF extension and lock unauthorized parties out of your documents. No need to download costly apps. Use Alto without paying a penny. Upload and password protect a PDF for free without limits.

Follow our guidelines and apply passwords to your PDFs:

  1. Enter AltoPasswordPDF in Chrome’s Web Store.
  2. Add the extension to your browser and click on it.
  3. Click Choose File and select the document you want to encrypt.
  4. Set up encryption by clicking Protect File Now!.
  5. Save the protected document or share it with others.

Note: make sure to give your recipients the file’s password.
AltoProtectPDF offers a reliable and fast solution for protecting your documents. Lock any PDF in clicks online. Secure your data with high-quality 128-bit AES encryption for free without registering an account.

BackgroundHow to password protect PDFs via Chrome

How to password protect PDFs using Windows

For those who use the Windows OS to handle documents, protecting PDFs with passwords can be challenging. Windows doesn't have a built-in solution for working with PDFs. But you can password protect a Word document and convert it to PDF. Encryption connected to the file will be saved and passed onto the new file type. Take note that any document in Portable Document Format opened in Word, changes its format to .doc/.docx automatically. 

Below are instructions for encrypting your document via Windows:

  1. Open the document you want to lock. 
  2. Click Info, which is located in the File menu.
  3. Select Protect Documents and then click Encrypt with Password.
  4. Enter your newly-created password twice to verify it. 
  5. Go back to the menu and click Save as>Portable Document File.

If you want to save more time, use an online solution and protect any PDF from being edited in clicks without having to convert anything or take any other other needless steps. AltoProtectPDF allows you to apply a password online for free. Just upload your document and enter a code. No need to install costly software or register an account. Try now for free!

BackgroundHow to password protect PDFs using Windows

How to password protect PDFs on Mac 

Mac users are lucky when it comes to being able to deploy built-in tools for online document management. These built-in features allow for the management of documents in many different ways; taking advantage of Preview you can sign, edit, and password protect PDFs. If your documents contain confidential information, it’s better to secure them before sharing.

Go over our brief instructions to learn how to password protect a PDF on a Mac:

  1. Go to Preview and open a file.
  2. Choose Export from the File menu.
  3. Put a checkmark in the Encrypt checkbox.
  4. Enter your password in the corresponding field (retype it to verify it).
  5. Click Save to make the changes permanent.

Receive your password-protected PDF in clicks without having to install an extra app on your computer or smartphone. Using a pre-installed solution saves time and resources. Plus, there’s no need to install specialized programs or search through online tools. Pre-installed features from macOS can lock, as well as protect your documents.

BackgroundHow to password protect PDFs on Mac 

How to password protect PDFs with Adobe Reader

Adobe Acrobat is a multifunctional solution for working on PDFs. In addition to viewing content, you can also edit it and set additional levels of protection. For example, using one of Acrobat’s tools, set a password for any PDF.  To use Acrobat for working with your PDFs, all you have to do is pay for a subscription and install the software to your computer, tablet, and smartphone. 

To password protect a PDF follow steps below:

  1. Open Acrobat and upload a file.
  2. Find Set Password located in the Tools sector. 
  3. Generate a strong code, following the password strength meter’s guides. 
  4. Click Ok to submit changes and save the encrypted document. 

Encryption with Adobe is a paid functionality, but you can use it with a 7-day free trial period. If you want to use a solution without having to create an account, pay for a subscription, or install any software, take advantage of AltoProtectPDF. Password protect your PDFs for free without all the traditional hassle and wasted time.

BackgroundHow to password protect PDFs with Adobe Reader

How to password protect PDFs using mobile devices 

Most people do business on the go: manage documents, share information, and even sign contracts. Therefore, having a device with advanced capabilities is very important. As a result, every platform for working with documents needs to develop a mobile version to remain competitive on the market. Programs for adding passwords to PDF documents are no exception. 

Follow the instructions below to learn how to protect the data in your files on any mobile device:

  1. Open your mobile browser and type AltoProtectPDF in the search bar.
  2. Choose the tool and click on it.
  3. Upload a document by clicking Choose File.
  4. Create secure encryption for the document.
  5. Click Protect File Now! and save the newly encrypted PDF file.

Various mobile apps help you work with PDFs seamlessly, but every device has limitations when it comes to memory space. AltoProtectPDF copes with this by providing you with a web-based solution, meaning you don't need to install any extra software to encrypt data. So, do more for less, faster, and at a higher quality than the tools you’re already using.

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How to password protect PDFs with iOS

AltoProtectPDF works and protects your PDFs regardless of the OS or device you’re using. Therefore, iOS users can utilize our service if they have documents with sensitive data to protect. AltoProtectPDF is a web-based solution, so you can work with document security online without having to install third-party apps. Get started without signing up or sharing personal info.

Follow the steps below to password protect your PDF on your iPhone or iPad:

  1. Go to AltoPasswordPDF via Safari or Chrome.  
  2. Use the Drag & Drop feature or click Choose File to upload a PDF.
  3. Enter a password and click Protect File Now!.
  4. Download or share the protected document for free. 

The process takes less than a minute. In addition to high-quality, the solution is free. Now you can manage your documents and handle tasks while on the go, using only your iOS device. In addition, use other AltoPDF tools and work remotely without worries. Try now for free!

BackgroundHow to password protect PDFs with iOS

How to password protect PDFs on Android 

If you are looking for a way to send documents with confidential information via your mobile device, AltoProtectPDF comes in handy. Our solution helps to password protect a PDF in clicks regardless of the device you’re on. No need to use a paid service, download an extra app, or register an account if plan on sharing sensitive data. 

Generate special encryption for PDFs using your Android with AltoProtectPDF:

  1. Upload your document to  using  the Choose File button.
  2. Select the PDF you want to lock from your internal storage or the cloud. 
  3. Come up with a strong password. 
  4. Type the password into the corresponding field. 
  5. Click Protect File Now! and then save your document.

In addition, you can find a lot more free tools for online document management with AltoPDF. Using our services is the most convenient and fastest way to manage your documents securely and properly.  Our server deletes your PDFs after each session, so feel confident knowing that no one can use or see your data.

BackgroundHow to password protect PDFs on Android 


How do I password protect a PDF for free?

AltoProtectPDF is a free online solution for PDF encryption. Upload a document and apply a password without paying a penny. Use the service regardless of the device you’re on and protect your data.