How to Add Comments and Sticky Notes to a PDF

PDF comments are annotations that attach notes to specific parts of a document without altering the underlying text or layout. A sticky note comment shows as a small icon on the page; clicking it opens a pop-up with your message. Text box comments display their content directly on the page. Both types are widely supported across PDF viewers and are the standard way to mark up documents for review, feedback, or internal reference.

Types of PDF Comments (and When to Use Each)

Before choosing a tool, it helps to know what you're actually adding:

How to Add Comments to a PDF on Mac (Preview)

Mac's Preview app supports sticky notes and text annotations with no additional software.

1. Open the PDF in Preview.
2. Go to Tools → Annotate → Note to add a sticky note, or Text to add a text box.
3. Click on the page where you want to place the annotation.
4. Type your comment in the note or text box that appears.
5. Drag the annotation to reposition it. For sticky notes, the icon can be moved independently of the pop-up.
6. Save with ⌘S. Annotations are saved into the PDF file.

Preview also lets you add a comment to a highlight: select text, highlight it, then right-click the highlight and choose Add Note to Highlight. The note is linked to that specific passage.

How to Add Comments to a PDF in Adobe Acrobat Reader (Free, Windows and Mac)

The free version of Adobe Acrobat Reader supports commenting on most PDFs. If the commenting tools are greyed out, the document has been locked by its creator — in that case, see our guide on removing PDF restrictions.

1. Open the PDF in Acrobat Reader.
2. Click the Comment button in the right panel, or go to Tools → Comment.
3. The comment toolbar appears at the top. Select the tool you want: Add Sticky Note, Add Text Comment, or Highlight.
4. Click on the page to place a sticky note, or select text to highlight and add a comment.
5. Type your comment and click outside to close the pop-up.
6. Save the file. Acrobat Reader can save commented PDFs locally via File → Save As.

How to Add Comments to a PDF in Microsoft Edge (Free, Any Device with a Browser)

Edge's built-in PDF viewer supports basic sticky note and text annotation without installing anything.

1. Open the PDF in Edge (drag it into an Edge window or right-click the file and choose Open with → Edge).
2. In the PDF toolbar, click the Add notes button (a pencil/note icon).
3. Click anywhere on the page to place a note. A yellow sticky note appears.
4. Type your comment and click elsewhere to close it.
5. Save the annotated file using the save icon in the toolbar.

How to Add Comments to a PDF on iPhone and iPad

iOS Markup supports text annotations and drawing, though not pop-up sticky notes in the traditional sense.

1. Open the PDF in the Files app.
2. Tap the Markup icon (pencil in a circle) in the top right.
3. Tap the + button in the Markup toolbar to access annotation types.
4. Select Text to add a visible text box, or use the pen/pencil tools for freehand drawing.
5. Position and resize the text box, type your note, then tap Done.
6. Tap Done in the main toolbar to save.

For full pop-up sticky note support on iOS, Adobe Acrobat Reader (free download) adds this capability. Open the PDF in Acrobat, tap the comment icon in the toolbar, and choose Sticky Note from the annotation menu.

How to Add Comments to a PDF on Android

As with highlighting, Android relies on third-party apps for PDF commenting. Adobe Acrobat Reader (free) and Xodo both offer full comment support.

Adobe Acrobat Reader (Android)

1. Open the PDF in Acrobat Reader.
2. Tap the comment icon (speech bubble) in the toolbar.
3. Select Sticky Note from the annotation types.
4. Tap on the page to place the note and type your comment.
5. Save the file from the menu.

Reviewing Comments: The Comments Panel

One advantage of proper PDF comment annotations over text boxes is that they appear in a Comments panel — a list of all annotations in the document, showing who added them, when, and the comment text. This makes review workflows much easier for documents with many comments.

In Acrobat Reader, the Comments panel is accessible from the right panel sidebar. In UPDF, it appears as a panel when you're in annotation mode. Preview on Mac doesn't have a dedicated Comments panel, but you can see all annotations in the Markup toolbar view.

Making Comments Permanent

By default, PDF comments are annotations — they can be removed by anyone with a PDF editor. If you need comments to be visible but non-editable (for archiving or printing), flatten the PDF. Our flattening guide covers this in detail. The key tradeoff: once flattened, comments become part of the page image and can no longer be read in a Comments panel or responded to in a review thread.

For Heavy Review Workflows

If you regularly mark up documents for client review, legal review, or team feedback, a dedicated PDF editor saves significant time. UPDF offers the full comment toolkit across Windows, Mac, iOS, and Android: sticky notes, text boxes, highlights with comments, strikethrough with notes, stamps, drawing tools, and an annotation summary export that pulls all comments into a separate document. The cross-platform sync is particularly useful for review workflows where different team members are on different devices.