How to Annotate a PDF for Free: Highlight, Comment, and Mark Up Any Document
Quick summary: To annotate a PDF for free, open it in Preview on Mac and use the Markup toolbar to highlight, add text, or draw. On Windows, open it in Edge and use the highlight, draw, or comment tools in the top bar. On iPhone, open the PDF in the Files app and tap the Markup pencil icon. All annotations save permanently with the file.
Annotating a PDF — highlighting important passages, leaving review comments, drawing arrows, or adding sticky notes — does not require expensive software. Every major operating system ships with tools that handle the most common annotation tasks. If you need to read, summarize, or ask questions about your annotated document afterward, our free AI PDF reader handles that in seconds.
How to annotate a PDF on Mac
Preview (built-in, free)
Preview’s Markup toolbar covers every common annotation type:
- Open the PDF in Preview.
- Click View → Show Markup Toolbar (or click the toolbox icon at the top right).
- Use the tools:
| Tool | What it does |
|---|---|
| Highlight (colored bar) | Highlight selected text in yellow, green, pink, or blue |
| Text (T) | Add a text box anywhere on the page |
| Note (speech bubble) | Add a sticky note attached to a point on the page |
| Signature | Draw or insert a saved handwritten signature |
| Draw (pencil) | Freehand drawing |
| Shapes | Rectangles, circles, arrows, speech bubbles |
| Underline / Strikethrough | Annotate existing text |
| Redact | Permanently black out selected text |
- Save with Cmd + S — annotations are embedded in the PDF.
Highlighting text in Preview
- Select the text you want to highlight by clicking and dragging.
- Click the highlight button in the Markup toolbar and choose a color.
- Or right-click the selection → Highlight Color → pick a color.
To change the highlight color of an existing highlight: right-click the highlighted text → Highlight Color.
How to annotate a PDF on Windows
Microsoft Edge (built-in, free)
Edge added full annotation support in recent versions:
- Open the PDF in Edge.
- The annotation toolbar appears at the top. Key tools:
- Highlight — select text, then choose a highlight color from the dropdown.
- Draw — freehand pen for underlining or circling.
- Erase — remove a drawing stroke.
- Add text — place a text box on the page.
- Add comment — (right-click on text → Add Comment in some Edge versions).
- Press Ctrl + S to save annotations.
Adobe Acrobat Reader (free tier)
The free Reader offers the richest annotation experience on Windows:
- Open the PDF in Acrobat Reader.
- Go to Tools → Comment.
- Available tools include: Highlight, Underline, Strikethrough, Add Sticky Note, Draw, Text Box, Stamp, and Measure.
- All annotations appear in the Comments panel on the right, with author name, date, and status.
- Save with Ctrl + S.
Acrobat Reader is free to download and does not require an Adobe subscription for annotation.
How to annotate a PDF on iPhone
- Open the PDF in the Files app (tap the file to preview it).
- Tap the Markup icon (pencil tip in a circle) in the top-right corner.
- The Markup toolbar appears at the bottom:
- Pen / Pencil / Marker — draw freehand.
- Eraser — remove strokes.
- Lasso — select and move drawings.
- Ruler — draw straight lines.
- Text (Aa) — add a text box.
- Signature — insert a saved signature.
- Shapes — draw geometric shapes with your finger, then Apple pencil-corrects them.
- Tap Done → Save File to embed the annotations.
For highlighting text specifically on iPhone: open the PDF in Safari (share from Files → Open in Safari), then press and hold on text to select it, and choose Highlight from the pop-up menu.
How to annotate a PDF online (free)
Several browser-based annotation tools work without sign-up. Search for “annotate PDF free” or “PDF annotator online”:
- Upload your PDF.
- Use the toolbar to highlight, draw, add notes, or add text boxes.
- Download the annotated PDF.
Privacy note: Online tools upload your file to a remote server. Avoid them for documents that contain personal, financial, or legal information.
How to add comments to a PDF
Sticky notes (Acrobat Reader)
Sticky notes are the most common review annotation:
- In Acrobat Reader: Tools → Comment → Add Sticky Note (or press S).
- Click anywhere on the page — a yellow sticky note icon appears with a text field.
- Type your comment.
- Click elsewhere to close; the icon stays on the page.
Recipients can open the note by clicking the icon, reply to it, or mark it resolved.
Text comments (Edge, Preview)
For a visible text annotation rather than a hidden note:
- Edge: use “Add text” to place a text box directly on the page.
- Preview: use the Note tool (speech bubble) for a floating sticky note, or the Text tool for a visible text box.
How to highlight text in a PDF
| Platform | Method |
|---|---|
| Mac (Preview) | Select text → Markup toolbar → Highlight button |
| Windows (Edge) | Select text → click Highlight in toolbar → choose color |
| Windows (Acrobat Reader) | Select text → right-click → Highlight |
| iPhone (Files Markup) | Not available for text — use freehand marker instead |
| iPhone (Safari) | Long-press text → Highlight |
Types of annotations and when to use them
| Annotation type | Best use |
|---|---|
| Highlight | Mark key passages for later reference |
| Sticky note | Leave a question or comment for a collaborator |
| Text box | Add visible notes directly on the page |
| Underline | Emphasize without obscuring the original text |
| Strikethrough | Mark text as outdated or incorrect |
| Freehand draw | Circle a diagram element, draw arrows |
| Shape (rectangle) | Draw attention to a specific region |
| Stamp | Mark as “Approved”, “Draft”, “Confidential” |
Frequently Asked Questions (FAQ)
Can I annotate a PDF without changing the original?
Yes. In Preview on Mac, use File → Duplicate before annotating to create a copy. In Edge, the file is not changed until you press Ctrl+S — close without saving to discard. In Acrobat Reader, annotations are saved when you save the file; they are separate from the original document content and can be hidden or deleted.
How do I remove an annotation from a PDF?
In Preview: click the annotation (highlight, note, or drawing) to select it, then press Delete. In Edge: right-click the annotation and choose Remove. In Acrobat Reader: right-click the annotation in the Comments panel → Delete. Freehand drawings are removed with the Eraser tool.
Why can’t I highlight text in my PDF?
The PDF may be a scanned image — there is no text layer to select. A PDF from a scanner or a photograph looks like text but is actually a picture. Use OCR software to convert it to a searchable document first, or use the freehand draw tool to mark up the image visually instead.
Will annotations appear when I print the PDF?
Yes, by default. In Acrobat Reader you can control this: File → Print → Comment & Forms dropdown → choose “Document” to suppress annotations, or “Document and Markups” to include them. Preview prints annotations by default; there is no built-in option to exclude them.
How do I annotate a PDF that is password-protected?
If a permissions password blocks annotations, unlock it first. See how to remove a password from a PDF for free. After removing the restriction, all annotation tools become available.
Can multiple people annotate the same PDF?
Each person can add annotations independently and merge the files afterward. In Acrobat Pro (paid), you can send a PDF for review and collect everyone’s comments in one file. For a free collaborative workflow, share the file via Google Drive and have each reviewer open a copy — then import comments from each copy into a master file using Acrobat.
Related guides
- How to highlight in a PDF for free — focused guide on text highlighting specifically
- How to edit a PDF for free — modify content, not just add notes
- How to redact a PDF for free — permanently remove sensitive text
- How to add a signature to a PDF for free — sign alongside your annotations
- How to flatten a PDF for free — lock annotations before sharing the final version