Annotate PDF on Mac: Free, Online, Native, Cross‑Platform & Research Tools Compared

You've been there: highlighting a key paragraph in Preview, closing the file, and returning to find your highlights vanished. Or trying to draw a circle with your trackpad – only to get a jagged mess. Searching "annotate pdf mac" throws up endless tool lists, but that's not what you need.

You need a clear answer: which tool fits your specific workflow, and how do you actually use it? This guide cuts through the noise. We classify tools into 5 real-world categories – free offline, online, native Mac, cross‑platform, and research‑focused – compare their annotation toolkits, and give you step‑by‑step how‑tos for every top pick. No more guessing – just annotating with confidence.

🎯Advance Notice: UPDF is the only Mac PDF annotator that offers a full annotation toolkit, built‑in AI assistance, seamless cross‑platform sync, and a one‑time purchase – making it the best value choice. 

How to Choose the Right Tools for Annotating PDF on Mac

Choosing a PDF annotator on Mac means balancing ecosystem integration, feature depth, and budget—here are five categories for every need.

Quick summary:

• Casual & free offline? → Preview (risk) or Okular/Skim (safe but curve learning).
• No installation? → Sejda / Smallpdf (risk for sensitive files, limited free quotes)
• Mac‑only pro? → PDF Expert (best trackpad) or PDFpen (best OCR).
• Windows + Mac + iOS + Android? → UPDF (best value).
• Academic deep reading? → LiquidText or MarginNote.

After analyzing the chart above, UPDF - a single license covers Windows, Mac, iOS, and Android; offers full annotation, OCR, conversion, batch processing, and AI chat/mindmap – all with a one‑time purchase. Its intuitive UI, offline privacy, and regular updates outperform Mac‑only or subscription‑heavy alternatives, making it the best value for most users. Let's check these 5 types of Mac annotators together.

How to Annotate PDF on Mac Online Free

Top picks: Sejda (more generous limits) or Smallpdf (simpler interface).

How to annotate with Sejda (online):

1. Go to Sejda.com > Edit PDF.
2. Upload your file (up to 200MB free).
3. Use the toolbar: Highlight, Underline, Strikeout, Sticky note, Text box, Freehand (mouse), Shapes, Signature.
4. Click “Apply changes” → download your annotated PDF.

How to annotate with Smallpdf:

1. Go to Smallpdf.com > Annotate PDF.
2. Upload (up to 50MB).
3. Tools: Highlight, Sticky note, Text box, Draw (mouse), Underline, Strikeout.
4. Click “Apply” → download.

Note: Online tools are great for quick jobs, but never upload sensitive/confidential documents.

How to Annotate PDF on Mac Offline Free

Top picks: Okular (cross‑platform) or Skim (Mac‑native) – both free, open‑source, and stable.
Avoid Preview for important work – use it only for casual viewing.

How to annotate with Okular on Mac:

1. Install via Homebrew: brew install --cask okular (or download from okular.kde.org).
2. Open your PDF.
3. Highlight: Click the highlight icon (or Ctrl+H), drag over text.
4. Sticky note: Click the note icon → click on page → type.
5. Freehand drawing: Click the pencil icon – basic drawing (no smoothing).
6. Export annotations: File > Export As > Annotations – choose plain text or XML.

How to Annotate PDF on Mac (Native Software)

Top pick: PDF Expert – unmatched for trackpad drawing and iCloud sync. But after the free trial, without purchasing plans, basic editing or annotating is not allowed. But UPDF allows free editing and annotating features even if you're not upgrade your account.

How to annotate with PDF Expert on Mac:

1. Open the PDF in PDF Expert.
2. Highlight: Select text → right‑click > Highlight, or ⌘+H.
3. Underline / Strikeout: ⌘+U / ⌘+Shift+S.
4. Sticky note: Click note icon → click page → type (⌘+N for new note).
5. Draw with trackpad: Click the pencil icon – now draw. Pressure‑sensitive smoothing makes your lines crisp – press lightly for thin lines, harder for thick.
6. Shape: Click the shape icon → add rectangle, oval, arrow, line – resize with handles.
7. Annotation sidebar: Click the sidebar (left panel) > “Annotations” – see all highlights, notes, and drawings grouped by colour and type.
8. Export summary: File > Export > Annotation Summary – choose text or Word. All comments extracted with page numbers.

How to Annotate PDF on Mac (Cross-platform Software)

Top pick: UPDF – identical UI on both platforms, one‑time payment ($79.99).
Alternatives: Adobe Acrobat (for industry compliance) or Foxit (for team collaboration).

How to annotate with UPDF on Mac (or Windows – identical):

• Highlight: Select text → click Highlight in the floating toolbar, or ⌘+H.
• Underline/Strikeout: Select text → choose from toolbar, or use shortcuts (⌘+U / ⌘+Shift+S).
• Sticky note: Click note icon → click page → type.
• Draw / shape: Click the pen tool – draw with trackpad (good smoothing). Click the shape icon for rectangle, oval, line, arrow.
• Signature: Click “Sign” – create using trackpad, camera, or upload image.
• Annotation sidebar: Click sidebar > “Comments” – filter by type or colour.
• Export summary: Click “Export” > “Extract Comments” – choose text or Word.

UPDF for Mac - the best PDF annotator provides the user with a complete set of annotation tools like highlights, underlines, pencils, shapes, notes, stickers, text boxes, erasers, etc.

Besides the solution to annotate PDF on Mac, if you want to know about the Windows solution, you can also learn the guidelines on how to annotate PDF on Windows from here.

How to Annotate PDF on Mac (Research‑Focused Software)

Top pick: LiquidText – unique visual workspace for linking ideas.
Alternative: MarginNote – if you also want mind‑maps and flashcards.

How to annotate with LiquidText on Mac:

1. Open PDF – right‑side workspace appears.
2. Highlight: Select text → click Highlight – the excerpt appears in your workspace.
3. Pull excerpts: Drag any highlighted text into the workspace – stack them side‑by‑side.
4. Link ideas: In the workspace, draw lines between excerpts to show relationships.
5. Add notes: Click the note icon in the workspace.
6. Export: Export > Outline – your linked notes become a structured summary.

How to annotate with MarginNote:

1. Open PDF – you see the document + mind‑map canvas.
2. Highlight: Select text – it appears on the mind‑map canvas automatically.
3. Add note: Click the note icon → type – it attaches to the highlighted snippet.
4. Create flashcards: Right‑click any highlight → “Create Flashcard” – perfect for studying.
5. Export: Export mind‑map as PDF, image, or to Anki flashcards.

FAQ

Q1: What annotation tools are included in a “Basic Set” vs “Full Set”?
Basic Set = Highlight, Underline, Strikeout, Sticky note, Text box, simple drawing. Full Set = Basic + Shapes (rectangle/oval/line/arrow), Signature, Stamp, Redaction, and often smooth drawing or OCR. Premium Full Set adds Audio notes, Bates numbering, or accessibility tagging.

Q2: Why do my highlights disappear in Preview?
Preview stores annotations in a separate .plist cache file, not inside the PDF. If you move, rename, or share the file, the cache breaks. Tools like Okular, Skim, UPDF, and PDF Expert embed annotations directly into the PDF – they never disappear.

Q3: Can I use Apple Pencil with any of these?
Yes – PDF Expert, UPDF, LiquidText, and MarginNote all support Apple Pencil on iPad (with Sidecar or direct iPad app). Preview also works but with fewer drawing tools.

Q4: Can I collaborate/share annotations with colleagues who use Windows?
Yes – if you use UPDF, annotations are saved as standard PDF comments and open perfectly in Adobe Reader, Foxit, or any PDF app on Windows. Preview’s annotations may not render correctly on Windows.

Conclusion

In this article, we have mentioned the best annotation tool on Mac that provides the desired type of work. The tool we have discussed to annotate PDFs on Mac is UPDF, and if you want to learn other PDF annotating programs, here are 5 PDF annotators for Mac. Generally, people prefer working on UPDF for its huge range of annotation tools. It also works great on the Mac M1 and M2 series, which makes it a preferable choice in the market.

If you switch between working on a Mac and an iPad, the synchronization and management of annotations are crucial. How to Annotate PDF offers workflow recommendations for cross-device annotation, helping you maintain efficiency and consistency across different platforms.