How to annotate a scanned document
To annotate a scanned document, open it in a tool that draws on top of image layers — not one that relies on selectable text, which scans don't have. Preview on Mac, Adobe Reader, or a browser-based annotator all work. Add arrows, text boxes, or sticky notes over the image, then save. To collect annotations from a client, share a link they can mark up in their browser without downloading anything.
On Mac with Preview
Open the scanned PDF or image in Preview (double-click it). Press Shift ⌘ A to reveal the Markup Toolbar. Because the file is a scan — not a text PDF — ignore the highlight and underline tools (they need selectable text). Instead use the Text Box tool to type a note and position it over the relevant area, or use the Arrow or Shape tools to point at what you mean. Press ⌘ S to save. The annotations are flattened into the file. If you're sending it back to someone for further review, this is fine; if you need the notes to stay as separate layers, export a copy first.
On Windows with Adobe Acrobat Reader (free)
Open the scanned document in the free Acrobat Reader. Go to View → Comment → Annotations. Because it's a scan, text highlights won't select anything — use the Sticky Note tool to drop a pin anywhere on the page, or the Drawing Markups panel to draw callout arrows or freehand lines over the image. Save the file. One catch: annotations may not render if the recipient opens the PDF in a non-Acrobat viewer — export a flat PDF copy before sending if you're not sure what they have.
In your browser with a free online tool
Smallpdf, Sejda, and PDF.net let you upload a scanned PDF and annotate it in the browser — no install. Upload, use the sticky note or draw tools, download the annotated version. Useful on any machine where you can't install software. Most free tiers cap file size at 5–10 MB and limit daily tasks, so for a typical scanned document they work fine; for large print files, check the limit first.
On iPhone or iPad with Markup
In Files, tap and hold the scanned PDF, then choose Markup. Or open it in Mail and tap the pencil icon. Markup gives you a pen, highlighter, text box, and shapes — all of which work on a scan because you're drawing on the image, not selecting text. Tap Done and share. If you photographed the page with your phone instead, the Photos app has the same Markup tools under Edit → the pencil icon.
When your client needs to annotate it, not you
Sending the file and asking the client to annotate it back creates a version problem. They download it, open it in whatever they have installed, mark it up — or take a photo of the page with arrows drawn in pen — and email it back. You now have two files and a 'the section near the bottom right' description that doesn't quite match. The cleaner path: share a link they open in their browser, click the exact area they mean, and pin a note right there. No file bouncing, no guessing which part of the scan they circled.
If a client is the one who needs to mark up the scan — not you — the fastest path is sharing it as a link. Drop the scanned document into Drafty, share the URL, and they click the exact area they mean and pin a note to it. No downloaded file, no re-emailing, no "which bit near the top?" Every comment lands in one thread, anchored to the spot on the scan.
Open a live demoQuestions
- Can you annotate a scanned PDF?
- Yes, but the key difference from a regular PDF is that text-based tools (highlight, underline) won't work because a scanned document is an image — there's no selectable text. Use sticky notes, text boxes, arrows, and freehand drawing tools instead. Preview on Mac, Adobe Acrobat Reader on Windows, and browser-based tools like Smallpdf all support this.
- How do I annotate a scanned document without printing it out?
- Open the scan in Preview (Mac), Adobe Acrobat Reader (Windows), or a browser-based tool. Use the drawing or sticky-note tools to add comments over the image. Save or download the annotated version. None of these require printing — annotations are added as a digital layer on top of the scanned image.
- What's the difference between annotating a scanned PDF and a regular PDF?
- A regular PDF has embedded text you can select and highlight. A scanned PDF is just an image of a page — text-based annotation tools don't work on it. You can still add sticky notes, text boxes, arrows, and shapes, but you can't highlight or underline words by selecting them. If you need text selection on a scan, you'll need OCR conversion first (Adobe Acrobat Pro or a separate OCR tool).
- How do I let a client annotate a scanned document without installing software?
- Share the scan as a link via a browser-based review tool. The client opens the link in their browser, clicks the spot they mean on the scan, and leaves a note pinned there — no download, no account. This avoids the emailed-file-back problem and keeps all feedback in one place.
- Do I need Adobe Acrobat to annotate a scanned PDF?
- No. The free Adobe Acrobat Reader (not the paid Pro version) supports sticky notes, drawing tools, and callout arrows on scanned PDFs. Preview on Mac and browser-based tools like Smallpdf and Sejda are also free alternatives that work on image-based scans.
- How do I convert a scanned document to editable text so I can highlight it?
- You need OCR (optical character recognition) to convert a scan to editable text. Adobe Acrobat Pro has a built-in OCR tool (Tools → Scan & OCR). Free alternatives include Adobe Acrobat Reader's "Fill & Sign" for simple cases, or Google Drive — upload the scanned PDF to Drive, right-click it, and choose Open with Google Docs, which runs OCR automatically.
Keep exploring
Stop emailing files back and forth.
Share one link. They comment on the exact spot — no account, always the current version.