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How to Password Protect PDFs Online Free (2 Ways)

In today's digital age, PDF files are commonly used for various purposes. This may include storing confidential data, such as financial reports, contracts, and personal information. It is, therefore, crucial to set password protection online to safeguard these files from unauthorized access.

This article will explore different methods to protect your PDFs, including free online tools and a more secure tool that can also manage access permissions.

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Part 1: Free Online Tools to Set Password for PDFs

There are various options available that allow you to set password protection for PDF online free.  

Here are two commonly used tools:

#1 Use "Smallpdf" for PDF Encryption

Smallpdf is a popular online tool that provides a simple and user-friendly platform to encrypt PDF online. 

Here's a step-by-step guide on how to use Smallpdf to password-protect PDF online:

  • Go to Smallpdf's website and select the "Protect PDF" option from the main menu.
smallpdf online pdf protector
  • Upload the PDF file you wish to encrypt by dragging and dropping it into the upload box or selecting it from your computer.
  • Once the PDF file is uploaded, you will be asked to enter a password to protect your PDF file. You can choose to add a password of your choice.
  • After entering the password, click the "Encrypt PDF" button to initiate the encryption process.
  • Once the encryption process is complete, you can download the encrypted PDF file by clicking the "Download" button.


  • Smallpdf also offers additional features, such as the ability to merge, compress, and convert PDF files, making it a versatile tool for managing your PDF files.


  • It is important to note that Smallpdf's free version has limitations, such as a maximum file size of 5 MB.
  • If you require more advanced features, such as higher encryption levels or larger file sizes, you may need to upgrade to the paid version of Smallpdf.

#2 Use Adobe Acrobat to Set Password Protection for PDF Online Free

Adobe's online tool provides a free and convenient way to encrypt your PDF files. Here's a step-by-step guide on how to password-protect a PDF with Adobe:

  • Go to Adobe's online encryption tool PDF files.
  • Click the "Select a File" button to upload the PDF file you wish to protect.
  • Enter a password in the relevant field. This password will be required to open the PDF file.
  • Click on the "Set Password" button to initiate the encryption process.
acrobat online pdf password protector
  • Adobe's online tool will encrypt your PDF file with the password and permissions you specified. Download the encrypted PDF file to your computer.


  • It’s a simple and energy-saving method.


  • The permission-control options are limited and Acrobat takes no account of the destination environment being used.

While Adobe's online tool provides an accessible and convenient option for password-protecting PDF files, it's important to note that it may not offer the same level of security as paid software tools.

Common Concerns of Using Online Tools for PDF Password Protection

Like the above, numerous free online tools offer a quick and simple way to add a layer of security to your PDF files without needing paid software or technical expertise.

drawbacks of using online PDF password protect

However, it's essential to understand that these free online tools may have some drawbacks regarding security and privacy:

  • Security Risks: Online tools store your PDF files on their servers for a certain period. This poses a risk to the confidentiality and security of your data. Data breaches or unauthorized access to your confidential data is always possible.
  • Limited Functionality: Most online tools provide basic encryption features and limited functionality. You may not have control over the encryption algorithm or level of encryption.  
  • Dependency on the Internet: Online tools require a stable internet connection to work efficiently. If you have a slow or no internet connection, it may be impossible to use online tools for PDF encryption. Besides, this increases the risk of data loss or corruption during the encryption process.
  • File Size Limitations: Online tools have file size limitations, which can be challenging if you have large PDF files to encrypt. You may need to upgrade to a paid version to encrypt larger files.

On the basis of the above analysis, it is essential to research and choose a reputable and trustworthy PDF encryption tool.  

Part 2: Encrypt PDF Files with a More Secure Tool

UPDF is one of the most reliable tools for providing secure encryption and access control to your PDF files.

It is a very efficient and user-friendly software tool that allows users to easily add password protection to PDF files by setting an open password, which limits access to the document, and a permissions password, which restricts actions like editing, copying, and printing.

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Here are the reasons why UPDF is a reliable tool for PDF encryption:

  • UPDF uses an advanced encryption algorithm, ensuring high protection for your documents.
  • With UPDF, you can manage access permissions for your PDF files, such as restricting printing, copying, and editing.
  • UPDF is compatible with various platforms Windows, macOS, Linux, iOS, and Android.
  • It can also be used to remove restrictions or passwords on a PDF.

Although UPDF is best known for its password protection feature, it has several other valuable features, such as:

  • Easy navigation and annotation tools to open, read, and annotate PDF documents.
  • Ability to edit the text in PDF documents with font, font size, and font color options.
  • Built-in image editor for inserting, replacing, resizing, copying, deleting, and cropping images in PDF.
  • Extraction, reordering, rotation, deletion, and addition of pages in PDF documents.

To encrypt your PDF document using UPDF, follow the simple steps given below:

Step 1: Open UPDF and the PDF Document

Download and launch the UPDF tool on your Windows/Mac computer or iOS devices. Then open the PDF file you want password-protected by clicking on the "Open File" button.

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Step 2: Click on the Protect Icon 

On the right toolbar, click the "Protect Using Password" icon.

UPDF protect using password

Step 3: Add an Open Password to the PDF

In the pop-up window, select the "Document Open" option to add an open password to your document. Choose a password of your choice to protect the PDF.

choose document open option of UPDF

Step 4: Set Permissions Password for PDF

If you want to restrict the PDF document's editing, copying, and printing, choose the "Permissions" option and add a password. Finally, click "Save" to save the PDF document and password protection.

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Watch the guide video below to learn how to protect PDF from data Leak.

Part 3: Extra Reading: How Strong is Adobe Password Protection?

While Adobe Acrobat is a commonly used tool to set password protection for PDF online free, some experts argue that Adobe password protection might not be entirely secure.

Some data security experts said that Adobe password protection relies on a weak encryption algorithm that can be easily cracked. Adobe password protect pdf online files have numerous vulnerabilities that make them unsuitable for protecting sensitive or confidential data.

They offer limited protection against exfiltration attacks while the PDF is in transit or at rest. They fail to prevent sharing, editing, or printing of the document as passwords can be easily shared and permissions can be removed in a matter of seconds.

The PDF format was not designed with security in mind, and Adobe added security controls as an afterthought. The primary focus has always been on convenience and shareability, and despite Adobe's efforts, protected PDFs can still be easily shared.

To safeguard PDF files, businesses should opt for specialized software designed to protect sensitive data.

Relying solely on Adobe encryption could lead to security breaches and compromise the integrity of confidential information.

Wrap Up

In conclusion, protecting your PDF files from unauthorized access is crucial in today's digital age.

While free online tools provide a convenient way to password-protect PDF files, they might not be entirely secure.

Therefore, using a more secure tool such as UPDF that provides advanced encryption standards and access control for your PDF files is advisable. Using these methods, you can keep your confidential data safe and secure from unauthorized access.

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