How to Annotate a PDF Online, on iPad, Mac and Windows
Quick answer: The fastest free way to annotate a PDF on any device is a browser-based tool. Open our free PDF annotator, upload your file, and use Highlight, Text, Note, Draw, shapes or arrows on the page, then download the marked-up PDF. No app, no signup and no upload. If you prefer built-in apps, iPhone and iPad have Markup, Mac has Preview, and Windows has Microsoft Edge.
This guide explains every free method, device by device, so you can pick the one that fits the PDF you are working on: a lecture handout, a contract you need to comment on, a form with mistakes to point out, or a draft that needs review.
What Does It Mean to Annotate a PDF?
Annotating a PDF means adding markup on top of the page without rewriting the original content. The most common PDF annotations are:
- Highlights to mark key sentences, numbers or clauses.
- Text and notes for comments, corrections, questions and reminders.
- Freehand drawing for ticks, circles, underlines and handwriting with a stylus.
- Shapes and arrows to frame a chart or point at a specific detail.
- Signatures and stamps, usually added as an image or drawn by hand.
Annotating is different from editing. When you edit a PDF you change the document itself, such as rewriting text or deleting pages. When you annotate, the original stays the same and your markup sits on top of it.
Method 1: Annotate a PDF Online (Any Device)
A browser tool works the same way on Windows, Mac, iPhone, iPad, Android and Chromebook, which makes it the easiest answer to "how can I annotate a PDF" when you are not sure what apps a device has. Here is how to do it with the PDF Buddy annotator:
Steps
- Open thepdfbuddy.netlify.app/annotate-pdf and click or tap the upload area. Choose a PDF up to 50MB.
- Pick a tool: Highlight, Text, Note, Draw, Rectangle, Circle, Line, Arrow or Image.
- Choose a color and a size, then drag on the page (highlight, draw, shapes) or click once (text and notes).
- Use Previous and Next to annotate other pages. Undo, Redo and Delete Last fix mistakes.
- Click Save Annotated PDF, then Download PDF.
What to know: the file is opened and saved in your browser, not uploaded to a server. When you save, the annotations are drawn into the pages ("flattened"), so they look identical in every PDF viewer, but they cannot be edited later as separate comments. Keep your original PDF if you might want to change them. The highlight tool marks the area you drag over rather than snapping to selected words, which also means it works on scanned PDFs.
Method 2: Annotate a PDF on iPad and iPhone (Markup)
Apple devices include a built-in markup tool called Markup, so you can annotate a PDF on iPad or iPhone without installing anything.
Using the Files app
- Open the Files app and tap the PDF to open it.
- Tap the Markup button (a pen tip icon). On some iOS versions it sits in the toolbar or behind a More menu.
- Choose a pen, highlighter or pencil, or tap the plus button for text, a signature or shapes.
- Tap Done to save the changes to the file.
The Books app can also open PDFs, and it offers Markup for PDFs stored there. With an Apple Pencil on iPad, handwriting and precise highlighting are especially easy. Menu names and icons move around between iOS and iPadOS versions, so if you do not see Markup straight away, look for the pen icon or the More (three dots) menu.
Prefer the same toolbar on every device, or need typed notes and arrows? Open the online annotator in Safari, pick the PDF from Files, and the download lands back in your Files app.
Method 3: Annotate a PDF on Mac with Preview
Preview is the default PDF app on a Mac and has a capable, free annotation toolbar.
Steps
- Double-click the PDF to open it in Preview.
- Click the Markup button (pen tip in a circle) to show the Markup toolbar.
- Select text and click the highlight button to highlight it, or use Text, Shapes, Note and Sign from the toolbar.
- Choose File > Save. Preview stores the annotations in the PDF.
Preview annotations remain editable in Preview and generally appear in other PDF viewers too. If you are on a shared or work Mac where you cannot use Preview, the browser method works in Safari, Chrome or Firefox.
Method 4: Annotate a PDF on Windows with Microsoft Edge
On Windows 10 and 11, Microsoft Edge is the default PDF viewer, and it includes free annotation tools.
Steps
- Right-click the PDF and choose Open with > Microsoft Edge.
- Use Draw in the PDF toolbar to write or sketch, choosing a color and thickness.
- Use Highlight to mark text, or select text and right-click to highlight it. Recent versions also have Add text and comment options.
- Click the Save icon (or press Ctrl+S) to keep your annotations.
Edge covers the basics well. For notes, shapes and arrows, try the PDF Buddy annotator in any browser. Adobe Acrobat Reader, a free download, also offers commenting tools such as sticky notes, highlights and drawing.
Method 5: Annotate a PDF on Android
Android does not have one PDF annotator that is built into every phone, because PDF viewers differ by manufacturer. Two free routes work well:
- Google Drive: recent versions of the Drive app let you open a PDF and use an annotate (pen) option with pen and highlighter tools. Availability depends on your app version.
- Your browser: open the online annotator in Chrome, choose the PDF from Files or Drive, and draw with your finger or a stylus. Text and Note work with the on-screen keyboard.
Method 6: Annotate a PDF on a Chromebook
ChromeOS opens PDFs in the Gallery app or in the Chrome browser. Gallery includes basic annotation tools, such as a pen and highlighter, and can save the result. Chrome's built-in viewer has also gained an annotation mode on some versions, though tools vary. For notes, shapes, arrows and images, use the browser-based annotator, which runs the same way on a Chromebook as on any laptop.
Which PDF Annotation Method Should You Use?
| Method | Devices | Install | Edit marks later | Best for |
|---|---|---|---|---|
| PDF Buddy online annotator | All, in a browser | None | No (flattened) | Quick markup anywhere, no upload |
| Apple Markup | iPhone, iPad | Built in | Varies | Handwriting with Apple Pencil |
| Preview | Mac | Built in | Yes | Text highlights and notes on Mac |
| Microsoft Edge | Windows | Built in | Partly | Drawing and highlighting on Windows |
| Adobe Acrobat Reader | Windows, Mac, mobile | App download | Yes | Comment threads and reviews |
Tips for Better PDF Annotations
- Use a color code. For example, yellow for key points, red for corrections and blue for questions.
- Keep the original. Save the annotated copy under a new name so you can always start again.
- Pair notes with arrows. A short note plus an arrow is clearer than a long paragraph in the margin.
- Zoom before drawing on a phone, and use short strokes or a stylus for neater marks.
- Finish the file. After annotating you may want to sign the PDF, redact sensitive details before sharing, or compress the PDF to email it.
Frequently Asked Questions
How can I annotate a PDF for free?
Use a free browser tool such as the PDF Buddy annotator: upload the PDF, add highlights, text, notes, drawings, shapes or arrows, and download the result. Built-in free options include Markup on iPhone and iPad, Preview on Mac and Microsoft Edge on Windows.
How do I annotate a PDF on iPad?
Open the PDF in the Files app and tap the Markup (pen tip) button to use pens, a highlighter, text, shapes and signatures, then tap Done. You can also open an online PDF annotator in Safari and use your finger or Apple Pencil.
Can I annotate a PDF without Adobe Acrobat?
Yes. Preview on Mac, Markup on iPhone and iPad, Microsoft Edge on Windows and browser-based tools such as the PDF Buddy annotator all let you highlight and comment on a PDF without Adobe software.
How do I highlight text in a PDF?
In Preview or Edge, select the text and choose Highlight. In the PDF Buddy online annotator, choose Highlight and drag a box over the text; it marks the area, so it also works on scanned PDFs.
Will my annotations show up in other PDF readers?
Annotations made with Preview, Edge, Markup or Acrobat are saved in the PDF and usually display in other readers. The PDF Buddy annotator draws marks directly onto the pages, so they look the same in every viewer.
Is it safe to annotate a PDF online?
It depends on the tool. Many online editors upload your file to their servers. The PDF Buddy annotator opens and saves the PDF in your browser, so the file is not uploaded. For confidential documents, follow your organization's policy.
Can I annotate a PDF on Android?
Yes. Recent versions of the Google Drive app include pen and highlighter tools for PDFs, or you can open an online annotator in Chrome and mark up the PDF with your finger or a stylus.
Ready to mark up your file? Open the free PDF annotator to highlight, draw, and add text and notes to your PDF in your browser. No signup, no watermark, and nothing is uploaded.