How to Highlight in a PDF for Free: Mark Up Any Document on Any Device
Quick summary: To highlight text in a PDF for free, select the text in Preview on Mac and click the highlight button in the Markup toolbar. On Windows, open the PDF in Edge, select text, and choose a highlight color from the toolbar. On iPhone, open the PDF in Files, tap Markup, and use the marker tool — or open in Safari to get true text highlighting. No Adobe subscription needed.
Highlighting is the most common way to mark up a PDF for study, review, or reference. Every major operating system includes a free tool that does this — no installation or subscription required. After marking up your document, you can upload it to our free AI PDF reader to get a summary or ask questions about the highlighted content.
How to highlight text in a PDF on Mac
Method 1: Preview (built-in, free)
- Open the PDF in Preview.
- Click View → Show Markup Toolbar (or click the toolbox icon top-right).
- Select the text you want to highlight by clicking and dragging.
- Click the highlight button (colored bar icon) in the Markup toolbar.
- The text is highlighted in yellow by default. Save with Cmd + S.
To change highlight color before highlighting:
- Click the small arrow next to the highlight button → choose yellow, green, pink, blue, or purple.
To change the color of an existing highlight:
- Right-click the highlighted text → Highlight Color → pick a new color.
Method 2: Right-click shortcut
- Select the text.
- Right-click → Highlight Color → choose a color.
The highlight is applied immediately without needing the Markup toolbar open.
How to highlight text in a PDF on Windows
Method 1: Microsoft Edge (built-in, free)
- Open the PDF in Edge (drag and drop, or right-click → Open with → Edge).
- Select the text you want to highlight.
- A small popup appears above the selection — click Highlight and choose a color (yellow, green, pink, or blue).
- Press Ctrl + S to save.
To remove a highlight in Edge: right-click the highlighted text → Remove Highlight.
Method 2: Adobe Acrobat Reader (free tier)
Acrobat Reader offers the most control over highlights on Windows:
- Open the PDF in Acrobat Reader.
- Go to Tools → Comment to show the comment toolbar.
- Click the Highlight Text tool (the marker icon), then select text — it highlights automatically.
- Or: select text first, then right-click → Highlight Text.
- Manage all highlights in the Comments panel (View → Comments).
- Save with Ctrl + S.
Highlight properties in Acrobat Reader: Right-click a highlight → Properties to change color, opacity (try 50% for lighter highlights), and author name for collaborative reviews.
How to highlight in a PDF on iPhone
Method 1: Safari (text highlighting)
Safari gives you true text highlighting on a PDF:
- Open the PDF URL in Safari (or share from Files → Open in Safari).
- Long-press on a word to select it, then drag the handles to extend the selection.
- In the popup menu, tap Highlight (you may need to tap the › arrow to see it).
- Choose a color: yellow, green, blue, pink, or purple.
- The highlight is saved in the PDF automatically.
Method 2: Files app Markup (freehand marker)
For scanned PDFs or when Safari is not available:
- Open the PDF in the Files app.
- Tap the Markup icon (pencil tip) in the top-right corner.
- Select the marker tool (thick stroke) from the bottom toolbar.
- Choose yellow or another color.
- Draw over the text manually.
- Tap Done → Save File.
This is a freehand drawing highlight, not a text-linked highlight — it is an image overlay rather than a semantic annotation.
Method 3: Apple Books
If you transfer the PDF to Apple Books:
- Open the PDF in Books (share from Files → Copy to Books).
- Long-press text to select → tap Highlight.
- Highlights are saved and synced across your Apple devices via iCloud.
How to highlight text in a PDF online (free)
Several browser-based tools let you highlight without installing anything. Search for “highlight PDF free online”:
- Upload your PDF.
- Select text and click the highlight button.
- Download the annotated file.
Privacy note: Online tools upload your file to a remote server. Avoid them for confidential documents.
How to change highlight color
| Platform | How to change color |
|---|---|
| Mac Preview | Right-click highlight → Highlight Color → pick color |
| Windows Edge | Right-click highlight → Change Highlight Color |
| Windows Acrobat Reader | Right-click highlight → Properties → Color |
| iPhone Safari | Tap the highlight → color dots appear below it |
| iPhone Books | Tap the highlight → color strip appears |
How to remove a highlight from a PDF
| Platform | How to remove |
|---|---|
| Mac Preview | Click the highlight → press Delete |
| Windows Edge | Right-click highlight → Remove Highlight |
| Windows Acrobat Reader | Right-click highlight → Delete |
| iPhone Safari | Tap the highlight → trash icon |
| iPhone Books | Tap the highlight → Remove |
How to highlight a scanned PDF
A scanned PDF is an image — there is no text layer to select. Two options:
- Freehand marker: Use the marker tool in Preview (Mac), Edge (Windows), or Files Markup (iPhone) to draw over the text visually. This is a drawing on top of the image, not a true text highlight.
- Run OCR first: Use Adobe Acrobat (Tools → Enhance Scans → Recognize Text), ABBYY FineReader, or a free online OCR tool to convert the scanned image into a searchable PDF. After OCR, text highlighting works normally. Our AI PDF reader can also read scanned PDFs and extract the content without needing OCR.
Frequently Asked Questions (FAQ)
Why can’t I highlight text in my PDF?
The most common cause is a scanned PDF — the text is an image, not real characters. Try selecting the text: if nothing highlights when you click and drag, it is a scanned document. Use the freehand marker as a workaround, or run OCR to make it selectable. A permissions password can also block annotations — remove it first (see how to remove a password from a PDF for free).
Do PDF highlights survive sharing?
Yes. Highlights saved to the PDF file are visible in any PDF viewer that supports annotations — including Acrobat Reader, Edge, Chrome, Preview, and iOS Files. Highlights saved only within an app (like Apple Books) may not transfer when you share the raw PDF file.
Can I export just the highlighted text from a PDF?
Acrobat Reader and Acrobat Pro can export comments (including highlights with the selected text) to a summary document: Comments → Export All To → Data File, or use the Comments panel → Print Comments Summary. For a free method, copy each highlighted passage manually or use our AI PDF reader to extract and summarize the key points from the document.
Will highlights print when I print the PDF?
Yes, by default. In Acrobat Reader, you can suppress annotations at print time: File → Print → Comment & Forms → select “Document” (no markups) instead of “Document and Markups.”
Can I highlight multiple colors to organize notes?
Yes — Preview, Edge, Acrobat Reader, and Safari all support multiple colors. A common system: yellow for key facts, green for definitions, pink for questions, blue for action items. The colors are just visual — they carry no semantic meaning unless you assign a system yourself.
Related guides
- How to annotate a PDF for free — add comments, sticky notes, and drawings alongside highlights
- How to copy text from a PDF for free — copy the highlighted passages into another document
- How to search a PDF for free — find text before highlighting it
- How to redact a PDF for free — permanently hide text instead of highlighting it