Highlighting text in a PDF is one of the most basic annotation tasks, and nearly every PDF viewer supports it in some form. Whether you're studying, reviewing a contract, or marking up a report, here's how to highlight on every major platform.
How to Highlight Text in a PDF on Desktop
In Adobe Acrobat Reader (free), select the text you want to highlight, right-click, and choose Highlight Text. Or use the keyboard shortcut Ctrl/Cmd + U. You can also open the Comment toolbar and click the Highlight tool, then drag over any text to mark it. Highlights are saved in the PDF and visible to anyone who opens the file.
In Microsoft Edge on Windows, open the PDF, select text, and a small toolbar appears โ click the Highlight option. Edge supports multiple highlight colors. On Mac, Preview's Markup toolbar includes a highlight tool accessible by clicking the marker icon after selecting text.
How to Highlight Text in a PDF Online
WukongPDF's PDF Editor includes a highlight tool in the annotation toolbar. Upload your PDF, select the highlight color, drag over the text to mark it, and download the annotated file. This works on any device with a browser โ useful when you're working on a shared or borrowed computer that doesn't have a PDF viewer with annotation support.
The online approach also makes it easy to highlight across a multi-page document and download a version with all highlights embedded, ready to share or archive.
How to Highlight Text in a PDF on iPhone and iPad
Open the PDF in the Files app or in Books. Tap and hold on a word to select it, then drag the handles to extend the selection. In the pop-up menu that appears, look for Highlight โ tap it to apply. On iPad with Apple Pencil, you can also use the Markup tools in the toolbar to draw highlights freehand over any part of the page.
The highlighting only works on PDFs with a proper text layer. For scanned PDFs where text isn't selectable, you'll need to run OCR first to create a text layer, or use the freehand drawing tool to draw over the relevant areas manually.
How to Highlight Text in a PDF on Android
Adobe Acrobat for Android supports highlighting: open the PDF, tap the pencil icon to enter annotation mode, select the Highlight tool, and drag over the text. Xodo PDF Reader & Editor also has a built-in highlight tool and saves annotations directly to the file. Both apps are free and available on the Play Store.
Highlighting Scanned PDFs
Scanned PDFs don't have selectable text, so the standard highlight tool won't work. You have two options: use a freehand drawing tool to manually draw colored marks over the relevant areas, or first run the document through an OCR PDF tool to create a searchable text layer. Once OCR is applied, the text becomes selectable and standard highlighting works normally with the PDF Editor.