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Top 5 PDF Annotator for iPad and iPhone in 2023 (iOS 17 Supported)

The PDF file format is the preferred configuration for documents as it helps them retain their designs appropriately. Then, it also enables document creators and users to keep their contents almost permanently. However, all these features may present complications. For example, they make PDFs challenging to edit. Often, users have to convert PDFs to editable formats such as Word to add such things as texts or images.

However, you don't need to go all through this as you can use PDF annotator iPad and iPhone apps. Analyzed here are the top mobile apps to annotate PDFs on iPad and iPhone.

Top 5 PDF Annotator Apps for iPad and iPhone

Several PDF annotator apps for the iPad and iPhone can be found in the Apple Store. However, you don't need to go through the stress of making a selection as we have narrowed down the list to the best possible five here. Some of these apps are generalist tools in that they can annotate PDFs on iPad and iPhone while doing other things. Alternatively, others are simply PDF annotation apps for iPad and iPhone and nothing else:

1)   UPDF

UPDF for iOS App would easily rank top of our choice of iPad annotation apps. Although it is a comprehensive PDF manager, the app contains a rich set of tools that make annotating and editing PDFs effortless.

These tools include the writing pen, shapes, stamps, strikeouts, erasers, and underlining.

With UPDF, you can alter your viewing setup, markup PDFs, add text to PDFs, edit PDFs, draw figures, and make comments in the margins.

how to annotate pdf on ipad updf

Beyond all the above, UPDF is a comprehensive PDF tool that enables you to access and manage various file formats. In addition, you can convert photos to PDF. There is an inbuilt smart scanner with which you take images and convert same into PDF.

Finally, your documents are safe as the app provides inbuilt security features such as Face ID and passcodes.

2)   Documents by Readdle

Documents by Readdle is a comprehensive file management app available for devices running iOS. With Documents, you can create and manage files of any type - videos, images, epubs, PDFs, and more.

pdf annotator ipad documents

However, one of its most important applications is its PDF function tool. The app does away with the notion that PDF files are uneditable and empowers users with the tools to modify them as desired. First, you can adjust the text on the PDF as you wish. For instance, you can embolden and increase the sizes of certain sections and highlight them using an attractive set of colors. You can also change the font colors or switch the font types altogether.

Then, when dealing with image-based PDFs, you get the tools to make them extractable, essentially converting them into text-based files. This also makes it possible to highlight sections of such PDFs, just as you would easily do with a text-based file.

3)   Notability

Although it is developed as a note-taking app, Notability has fast become one of the best PDF annotation apps for iPad and iPhone. Packed in an app with a properly organized and color-coded interface, Notability combines document and notes management capabilities with premium PDF editing tools.

annotate pdf on ipad notability

In addition to what other PDF annotation apps on iPad can do, Notability contains trendy features such as the ability to merge documents. Essentially, users can combine various PDF documents into one while perfectly retaining the formatting. In the course of editing documents, you can also import images and highlight texts with multiple colors. In addition, there is a Bookmarking feature, making it possible for users to quickly locate certain pages later. If, after making all the necessary edits, you wish to share the note with others, Notability also makes that effortless. You can send the document out using just a link.

A key feature of Notability is that it provides top-notch tech that most other iPad annotation apps don't offer. One of such is the handwriting-to-text tool. While other PDF annotation apps for iPad enable you to make notes with your hands, you should note that free handwriting has its downsides. For instance, not everyone can grasp the writing. However, Notability has AI tools that recognize these handwritten notes and convert them to texts in computer fonts.

The most advanced feature is the audio recording tool via which users can take down voice notes and embed them within the PDF document. You will agree that often, people are more expressive in speech than in writing. As such, getting their thoughts down using their own voices is a highly desirable feature.

In addition to the above, you are given the tools to keep your documents private by putting a password over them.

4)   PDF Expert

PDF Expert is another software that makes the list of best apps to annotate PDFs. While it can perform several other standard PDF annotation functions, PDF Expert further enables signing and filling. Thus, if your PDF document is a form, letter, or contract that requires signing or filling, then PDF Expert is your tool.

pdf annotator app pdf expert

Furthermore, you can export them from one PDF document to another after making your annotations.

Importantly, it is one of the few best annotation apps for iPad that allows for collaboration. Thus, you can make comments while working with others on documents.

Finally, whatever you do on the app syncs across all devices - iPhone, iPad, and Mac.

5)   iAnnotate 4

iAnnotate is another top contender for the best annotation app for iPad and iPhone. One of its most unique features is the writing experience, as it enables making notes on a PDF, just as you would have it on paper. Then, after making the annotations, you can drag and drop them in any part of the document.

best pdf annotation app for ipad iannotate 4

Other things you can do with iAnnotate include strikeout, signature, and making sound clips to embed within the PDF.

How to Annotate PDF on iPad

Of all the apps discussed above, UPDF offers the best combination of features. As such, we would be discussing, in brief, steps to annotate PDF on iPad.

  1. Launch the UPDF and search for the PDF file you wish to annotate. The PDF file can be on your phone storage or the cloud.
  2. Click the "Comment" icon on the top-right corner. Select the section of the document you wish to annotate.
pdf annotation app ipad

3. There are various tools for annotating, including a highlighter, marker, and eraser to make corrections.

4. Tap the annotation tool using your fingers or Apple Pencil, although the Pencil appears to give a more seamless experience.

5. Click on "Save" to save the changes made.

How to Annotate PDF on iPhone

The process for annotating PDFs on the UPDF app is similar to the iPad. The downside is that you cannot use the attractive tools on the Apple Pencil. Nonetheless, you can achieve just as much with the UPDF iPhone app.

  1. On the PDF file, navigate to the array of available annotation tools, including a handwriting tool/pen, highlighter, and underline tool, among others.
  2. You can further set the color and thickness for the highlighter and handwriting tool.
  3. After selecting the tool to use, navigate to the document section where you wish to apply the tool.
  4. If you make mistakes, for instance, applying the tool in the wrong section, an eraser is available to undo them.
best app to annotate pdf


Annotating tools for PDFs provides lots of utility as they enable you to bring more life to the document. This converts the PDF file from one which is uneditable to a seamlessly alterable document.

Nonetheless, it is essential that you use only the best annotation apps for iPad and iPhone when annotating. We have conducted thorough research and have outlined the top five here. And we introduce UPDF as the first one, because of its useful and variety function. Markup, adding text, adding shape, adding notes, and highlight PDFs can be easily done in UPDF.