PDF Annotator Review – 8 Best Methods to Mark up a PDF on Different Platforms
Last Updated on September 21, 2025 by Tina Clark
PDF is the file format frequently used for business purposes. When you need to annotate or make up a PDF, what are the best PDF annotators you should try? Whether you need to add some comments to the PDF documents on an Android phone or a computer, here is the PDF annotator review with the 8 best tools you should not miss.
Part 1: 4 Best PDF Annotators on Windows and Mac
PDFelement
PDFelement is more than a high-quality PDF annotator and editor. It is designed similarly to Microsoft Word, which makes the program more straightforward for those who are already familiar with Microsoft Office products. Moreover, it has a wide range of tools to add annotations to your PDFs and connect with your colleagues, including underline, strikethrough, shapes, sticky note, text fields, and hand drawings.
Pros:
1. Add sticky notes, text boxes, and freehand drawings to make notes on PDF.
2. Annotate with highlights, underlines, or strikethrough texts in documents.
3. Alter the text, links, images, and pages of a PDF document in several ways.
4. Tweak the different parameters for editing and annotating the PDF files.
5. Provide built-in OCR algorithms to make the image-based PDF searchable.
Cons:
1. Cannot create PDF with video or insert the video files into the PDF files.
2. Take too much time for editing the PDF file or downloading the program.
Adobe Acrobat Reader
Adobe Acrobat Reader is another frequently used PDF annotator, which provides entry-level features with a variety of PDF annotating tools. It offers everything, from making comments to rotating your PDF documents. Signatures and modified PDFs may be easily added to and stored in the system. Moreover, it allows users to quickly and easily print documents in different templates and themes.
Pros:
1. Compatible with a wide range of web browsers with configuration options.
2. Convert office formats and pictures to PDF in a quick and simple manner.
3. Collect and manage all your feedback and comments within one place.
4. Manage your project with the ability to send reminders, close workflows, etc.
Cons:
1. Need to upgrade to the full version to use the PDF text editing features.
2. Lack some high-powered OCR proofreading tools and annotation tools.
Preview
Preview is a built-in PDF annotator for Mac that enables you to add texts to PDF documents, annotate, highlight, sign, and insert comments. When you take some notes on one page and then decide to move them to another, you can effortlessly transfer them from the previous page. If you have a camera, it enables you to add a signature to your writing by just capturing it. Moreover, there are features to export the desired PDF easily.
Pros:
1. Provide the built-in features to browse and edit PDF files free of charge.
2. Add images and pages as the annotation to the desired PDF documents.
3. Crop, fit, re-size, and encrypt PDF files, and add images, among others.
4. Free PDF annotator with the basic features to annotate and view PDFs.
Cons:
1. Lack of some advanced features, such as the OCR algorithm and editing.
2. Cannot add texts to PDF files or add special annotation/comment to PDF.
Microsoft OneNote
Microsoft OneNote is more than a cross-platform digital notebook app for Windows, Mac, and the web. It allows you to annotate PDF files and includes a variety of versatile and powerful annotation tools, including drawings, lists, clippings, images, and tables. When you need to mark up PDFs from different devices with the same pattern, Microsoft OneNote is one of the most intuitive PDF annotators available.
Pros:
1. Annotate and mark up the PDF voice, texts, videos, and other elements.
2. Provides cloud storage and note synchronization across several devices.
3. Share your work on social media platforms, such as Facebook and Twitter.
4. Turn handwritten circles and other shapes into perfection via Ink to Shape.
Cons:
1. Cannot search for the desired texts from the PDF directly from OneNote.
2. It is impossible to export the annotation PDF to your computer or device.
Part 2: Top 4 PDF Annotator Apps on Android and iOS
Xodo PDF Reader
Xodo PDF Reader & Editor is one of the most popular PDF annotators and readers for Android. You can simply create PDF files from your camera, from images, or from Office documents. It allows you to markup PDF files, annotate them, fill out forms, and collaborate with others. Moreover, it has smart integration with Dropbox, Google Drive, and OneDrive and syncs the edits with Cloud services between different devices easily.
Pros:
1. Compile the Office documents and image files into a brand new PDF.
2. Annotate and sign PDF documents and sync with others in real-time.
3. Draw and write directly on PDF files highlight and underline texts, etc.
4. Sign contracts, expense reports, cover letters, or any other document.
Cons:
1. Download to the internal memory of your device rather than the SD card.
2. Unable to add annotations to PDFs with audio files as the rival PDF editors.
PDF Expert
PDF Expert is a popular PDF annotator for iPhone. By using the term Expert in your moniker, you instantly establish a high bar for yourself, which will not let you down. Apart from the standard functions that a strong PDF annotator should include, such as adding notes and comments, changing the font style and color, highlighting, and filling and signing forms, PDF Expert also includes custom stamps.
Pros:
1. Generate frequently used stamps for annotating and providing input.
2. Draw on pages and even photos with the Apple Pencil or your fingers.
3. Sync and connect to data stored on all main cloud storage providers.
4. Provide multiple markup tools, illustrations, or sketch to mark up PDFs.
Cons:
1. Need to purchase add-ons to extend more features with a PDF annotator.
2. Only enables to convert files to image-based PDF without OCR features.
iAnnotate PDF
When you need to mark up PDFs on your iPhone or iPad, iAnnotate PDF is a powerful PDF editor for annotating PDF documents. It strikes the ideal mix between giving necessary tools and maintaining an attractive user interface. Moreover, it enables you to scan the images to the desired PDF files. It has UI emulates a desktop PC, which allows you to use the touch screen to mark up PDFs on an Android device.
Pros:
1. Annotate PDF files via Apple Pencil and pan, zoom, scroll with your fingers.
2. Provide pen, highlighter, typewriter, stamp, straight-line, note, strikeout, etc.
3. Compress your annotations onto the documents to prevent modification.
4. Web mark up to annotate the website you have found and save it as a PDF.
Cons:
1. No way of adding a blank space next to the PowerPoint to write notes on.
2. It is difficult to sync the PDF files between different Cloud services online.
PDF Max
PDF Max is another dependable PDF annotator app for annotating, viewing, and modifying PDF files directly from your Android device. It enables you to create documents with handwriting and highlights, insert stamps and text, and even sign and modify PDF files. Moreover, you can also use your fingers to take handwritten notes or highlight the texts in books, whether normal PDFs or scanned documents.
Pros:
1. Annotate the PDF documents via highlight, underline, and cross-out tools.
2. Create voice memos and embed them into the final PDF as the annotation.
3. Support complex form field validations and calculations are on hand easily.
4. Provide the thread conversions to collaborate with others like never before.
Cons:
1. Need to subscribe to Pro version monthly to explore the full functionalities.
2. The reading out loud TTS feature does not work with all the languages well.
Part 3: FAQs about How to Annotate and Markup PDFs
Conclusion
When you need to annotate PDF documents, you can learn more about the 8 best PDF annotators from the article. Increase your efficiency at work by utilizing convenient programs such as the ones described above. It's crucial to pick one that's filled with critical and helpful features that meet your specific demands.