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How to Flatten PDF Online - The Newest Guide in 2024

Flattening PDF files is a very assistive feature, especially for confidential and private PDFs. If you want to make a PDF file readable only and restrict editing in it, there is no better way than PDF flattening. There are a few web-based tools that can help you in flattening a PDF file online.

The number of PDF tools that can help you with PDF flattening online is limited. It is usually not recommended to flatten PDF online as online tools are not safe and stable. To make the flattening process more convenient, we will discuss a top-rated offline PDF editor - UPDF who can do this task professionally. You can try it by clicking the free download button below.

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Part 1: Can I Flatten a PDF Online?

Yes, you can use a web-based tool to flatten a PDF file to restrict further editing. This is also very helpful for preserving the copyrights of a PDF. However, the numbers of online PDF flatteners are not diverse, and only a few tools support this feature. Even some popular tools like Smallpdf and iLovePDF do not support this feature. So, you first need to find one to flatten a PDF file on an online platform.

Part 2: How to Flatten a PDF Online?

When it comes to flattening a PDF online, you need to work with a reliable tool. Make sure the PDF tool you use has an acceptable data policy so you don't have to face any data breaches. Moreover, always use a tool with a well-organized user interface so you can easily use any feature. For flattening a PDF file online, you can use the following steps listed here:

  • Step 1: On your browser, search for an online PDF flattener, and from the results, launch one of the topmost tools. From the main interface of a tool, follow the instructions and upload the PDF you want to flatten.
  • Step 2: Following this, you may see options like flatten everything or flatten form field only, select the option of your choice and continue with the flattening procedure.
  • Step 3: Once the flattening procedure is completed, you are good to download the flattened PDF file. After saving the file on your device, you can now use it as per your need.

Part 3: Advantages and Disadvantages of Flatten PDF Online

Users mainly use online tools, so they don't have to go through the downloading procedure and save the device's memory. However, there are both merits and demerits of an online tool which you should know before using it. Therefore, here are some of the common points regarding the advantages and disadvantages of a tool that you can face while using it:

Benefits of an Online PDF Tool

  • When you work with a web-based tool, there is no need to download it, as you can use its feature on the website. All tool features will be accessible to you in one place, and you don't have to explore the tool thoroughly.
  • All the work in an online PDF tool is automated, so there is no complicated procedure. A PDF can be flattened online very easily as you just have to upload a file, follow simple instruction and save it.
  • The online tool is used on a web browser, so you don't have to worry about its compatibility. No matter if you are working on a Mac, Linux, Android, iOS, or Windows platform, you can use the online tool without any issues.

Drawbacks of an Online PDF Flattener

  • By using an online PDF flattener, you will not be able to edit the PDF files directly. As PDF editing requires an enhanced computing engine and powerful algorithms, thus you can face difficulties editing PDFs online.
  • You can face difficulty operating an online tool as it requires an internet connection. If your internet is interrupted or its speed is slow, you have to wait the whole time to get your file flattened.
  • No online tool can work perfectly with large-sized files. Some tool even has file size restrictions that you have to follow, thus showing the downside of their functionality.
  • Security issues, data policies, and encryptions in an online tool are not very reliable. Imagine you flatten a confidential PDF file to restrict further editing; however, if the online tool gets hacked, the PDF will become accessible to unauthorized personalities.

Comparison Table Between the Online and Offline PDF Tool

There are both online and offline PDF flatteners that you can use to flatten the PDF file. However, offline PDF flatteners are preferred because you don't have to face any file size restrictions or data loss issues with them. UPDF is one of the most intuitive offline PDF tools which can help you in many ways. Whether you want to edit, convert, compress, organize or flatten a PDF file, this tool can help you with everything.

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If you are still confused between an online and offline PDF tool, then check the following concise table to understand more differences between these two versions:

FeatureUPDFOnline Tool
File Size LimitationNo LimitationMax 2 - 4GB
Security  The offline tool ensures high security of your documents and all your documents are stored on your local storage.Online tools require you to upload your confidential documents to the web, and they may be attacked by hackers easily.
LagNoDepends upon the internet.
Editing PDFsYes, you can use UPDF to edit the existing text on your PDF document easily.No, no online tools allow you to edit existing text on your PDF document.
OCR PDFsYesNo, not supported by all free versions of online tools.
Flatten PDFsYesOnly a few online tools support this feature.
Speed Rating4.8(UPDF is faster than Adobe Acrobat)3.2
Performance Rating4.83.5
Functions Richness4.83.3
Overview Rating4.83.4

Part 4: How Can I Flatten a PDF Offline?

UPDF is a one-stop solution for all PDF problems. Moreover, the security and data policies of this tool are much more reliable than online PDF tools. If you want to flatten a PDF file offline with this exceptional tool, feel free to follow the steps listed underneath:

Step 1: Launch UPDF and Import PDF

Download UPDF on your device and launch it. From the main interface, click on the "Open File" button to select the PDF file of your choice, and hit "Open."

Step 2: Initiate the PDF Flattening Process

Once the PDF file is opened, click on the "Save as Other" icon from the right panel. From the menu, select the "Save as Flatten" option, and by this, you'll see a prompt window of option. From the list options of "Flatten Annotations and Form," "Flatten Watermarks," and "Flatten Cropped Pages," select the option of your choice. You can also choose all options for the same PDF file.

flatten pdf online with updf

Step 3: Save Flattened PDF

After selecting the flattening options, click the "Save As" button and choose a path to save the flattened PDF file on your device.

save pdf flattening online

Video Tutorial on How to Flatten PDF


This article demonstrates that there are few tools on the web that you can use to flatten PDFs online. While selecting one, you must take both advantages and disadvantages of online PDF tools into account. There can be some irritating restrictions that you can face while using them, but desktop tools don't have these limitations. Thus, you can use a reliable PDF tool, UPDF, to make your work easier. From compressing to flattening a PDF file, this tool has satisfactory outcomes. Click the button below to give it a try.

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