PDF Highlighters Online: Pros & Cons, Recommendations & Offline Alternative

We are often given documents that need basic editing like adding colors, shapes, pictures, text, etc. But for a beginner, it becomes hard to find the correct tool as there are a huge number of PDF highlighting tools present digitally. These can be available across the internet and can be used from any OS device. In this article, we have written detailed sections on the top 5 online PDF highlighters. These highlighters are the best source for adding different markups, notes, graphics, and designs to your documents.

Before we introduce the 5 best online PDF highlighters, you should be aware of the disadvantages of online services, such as the safety issue, stability, limitations, etc. So we also introduce UPDF for you at the end of this article, and it is the best PDF highlighter for Windows, Mac, iOS, and Android. You can try it for free by clicking the "Free Download" button.

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Part 1: Top 5 Online PDF Highlighters

Your teacher rejects your science project because it lacks different colors and texts that would change the outlook. What will you do in such a situation? Do you know about any efficient PDF online highlighter free that can do the job for you? Here are a few PDF text highlighters online that you can use to enhance your document:

1. PDF Bob - Online Free PDF Highlighter

PDF Bob is an online PDF highlighter free with several options to alter PDF documents, the finest of which is annotated PDF. This mode might help you improve your project and make it more appealing. Different shapes, like circles and rectangles, are available as annotation tools in PDF Bob. You can use a circle to create many diagrams, while a rectangle can be utilized to hold a considerable amount of data in that diagram.

pdfbob online free pdf highlighter


  • You can use the "Highlight text" function if you want to bring your readers' attention to a particularly essential piece of information.
  • Unlike other tools, you can save the PDF file without a watermark while editing it using PDF Bob.
  • You can use the "Arrow" tool to draw attention to a certain topic.


  • This tool, PDF Bob, doesn't allow you to upload the document from any Cloud storage.
  • It doesn't support the signing feature.
  • Lacks advanced features, such as OCR, flatten, PDF/A, etc.

2. pdfFiller - Free Online PDF Highlighter

Have you lost track of an important document that you modified with pdfFiller and saved to your computer? Don't worry; pdfFiller is a PDF online highlighter for PDF files that saves your edited documents. It's a simple PDF highlighter with a variety of editing features for your business papers. If you're sending the document to a corporation, you can use the "Highlight" option of this great PDF text highlighter online to bring attention to important context components.

pdffiller online free pdf highlighter


  • pdfFiller has a unique and vast signature feature which includes a webcam to catch the initials of your signature.
  • The "Date" tool has made the job easy. When you add the date to a PDF document, it looks professional and official.
  • It also provides a "Blackout" that you can use to hide any critical information inside your PDF file.


  • This PDF editor's "Highlight" tool will let you draw a box on the text instead of highlighting only the text.

3. PDF4me - PDF Online Highligter

If you're looking for a powerful yet easy-to-use PDF online highlighter free, go no further than PDF4me. It comes with all of the capabilities you'll require for your documents. Let's assume your supervisor didn't approve the dealer's quotations; thus, you can return the document with a "Not Approved" stamp. This can be performed by using the "Stamp" and "Watermark" tool, which includes 12 unique stamps with which you can update the status of your document.

pdf online highlighter pdf4me


  • If you are worried about protecting your client's sensitive information, use the "Generate and Add QR Codes" tool to lock the secret codes.
  • PDF4me also allows you to lock any annotation after adding it properly to your PDF.
  • It has versatility in editing options. To edit a PDF file, you have to just drag and drop it.


  • You are provided with specific colors only for annotation.
  • It is a simple online PDF highlighter without any advanced features.

4. Smallpdf - Free Online Highlighter

This is the free PDF text highlighter online that you should use to edit your documents. The interface offers powerful yet simple-to-use tools to assist you in improving your work. If you need a highlighter to highlight key aspects, Smallpdf offers two different highlighters. One is a text highlighter, while the other is a freehand highlighter in which you can highlight the text in any direction.

smallpdf online pdf highlighter


  • You can use the "Pencil" tool to add key pointers to the page and the "Eraser" to delete any undesirable annotation.
  • You can add pages and PDF files to an existing PDF document and split it into two separate PDFs by using the split feature.
  • With this PDF highlighter online, you can select any page and change its rotation to left or right.


  • The tool doesn't provide you with a renaming option when you download a condensed file. The file gets renamed automatically.
  • I tried the highlight feature of this tool and found that you can't highlight the text correctly. You can tell from the screenshot I take to see the real highlighting effect.

5. Sejda - PDF Online Highlighter

Unlike other PDF highlighters online for free, Sejda allows users to edit pre-existing documents and make use of it by using its OCR feature. The Text tool is so helpful and has a variety of font styles, sizes, and colors; this can be used to fill out forms as well. The annotate feature opens up many great options for you, like using the "Strike Out" tool to cancel or delete any false information that will negatively impact the future of your business.

sejda online pdf highlighter


  • While signing the PDF document, you can rotate the signatures in a vertical and horizontal way, as per your page's requirement.
  • The freehand highlighter facilitates you by highlighting the important points on that document and not the whole text.
  • The watermark feature will help you design a watermark that secures the important information related to your work as nobody can change it.


  • Some online PDF highlighters restrict the length of PDF documents, and Sejda is one of them. It restricts it to 200 pages in length.
  • When you use this tool to edit the existing text in your PDF, it will change your original font and damage the original layout.
  • As you can tell from the screenshot above, this tool can't highlight the correct text or area for you.

Part 2: Limitations of Online PDF Highlighters

Online PDF highlighters are widely available all across the internet, and people tend to use them on a daily basis because they can be accessed from any device. But due to some limitations, there are still many people who prefer offline PDF highlighters. Some of the limitations are discussed in this section.

  • Let's say your internet connection is bad, then it becomes hard for you to work online. This results in slow speed, and there is a high chance for you to lose track of the data.
  • Also, if the internet is causing a problem or is working slowly, then you won't be able to upload large files. With that, most PDF highlighters online have file size issues; you cannot upload a file larger than a specified size.
  • The major concern of online PDF highlighters is safety. You will have to upload your document to third-party websites and there may be an information leak.
  • Most online PDF highlighters only have simple annotation tools without variety. And there are no advanced features, for example, if you want to edit the text or perform OCR, most online tools can't help you.
  • Lastly, all online tools claim that they are free. However, there are always many limitations, such as the file size, the file number per day, etc. They are not really free if you want to upload more documents or large documents.

Part 3: A Better Alternative to Online PDF Highlighters

After learning the disadvantages of online PDF highlighters, you may want to seek an alternative. Offline PDF highlighters are used and preferred by most people in this digital age. Offline PDF highlighters are more versatile and easier to use as they are compatible with Mac and Windows, and you can use them without any limitations.

One of them is UPDF, a wonderful tool for all business professionals or people of any profession. This tool is easy to use with robust highlight features. It allows you to highlight PDFs with various colors and tools. You can download it now to use all the dedicated tools.

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updf pdf highlighter

Once you download this PDF highlighter, you'll instantly begin to enjoy the most delightful interface design with multiple options. You can easily highlight, underline, strikethrough, squiggly, and add a text box, callout, sticky note, stamp, or signature to your PDF file.

To make your content look fascinating, you can add shapes of different colors like rectangles and ovals; this will help you draw the reader's attention. You can also fill these colored shapes with suitable text; the text can be highlighted, strikeout, and underlined as per the demand of the document.

markup pdf with updf pdf highlighter

The advanced interface lets you open multiple tabs and view as many PDF files as you need to in a go. With that, you can use the page layout options to adjust the page views according to the fit of your screen.

Adding bookmarks to the document by using UPDF will make it look more presentable, just as you do your books in real life. You can also use this tool to edit, convert, OCR, protect, and share PDF documents.

If you want to learn detailed instructions on how to use this software, please watch the video below.

Part 4. Comparison of UPDF and Online PDF Highlighters

UPDFOnline PDF Highlighters
InternetNot needNeed
Highlight Color100+ Colors and customizable1-6 Colors
Other Annotation Features (Text Box, Stamps, Sticky Notes, etc.)Yes, UPDF provides all kinds of annotation tools.Only a few tools are supported.
Manage Annotation List
Advanced Features
OCR Feature
StabilityVery stableNot stable due to the internet situation.

After comparing UPDF with online PDF highlighters, you may find that UPDF provides more options for highlighting and other advanced tools. It is the best choice if you want to make your PDF documents attractive and fascinating. What's more exciting? It now offers a big discount if you purchase UPDF with the AI add-on, and you can upgrade now to enjoy the exclusive discount.

Wrapping Up

In this article, we have discussed both offline and online PDF highlighters that are exceptional in their own way. We have suggested five amazing PDF highlighters online for free with a number of different pros and cons. On the other hand, you should be aware of the pros and cons of online tools. The pro is that you don't need to download any software, however, there are several disadvantages, such as it is not safe and stable to use online tools. That's why we introduce an amazing offline PDF highlighter named UPDF which is preferred to be one of the best offline PDF tools. You can download and try it now.

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