How to Highlight Text in a PDF for Free

PDF highlighting is a standard annotation type — it adds a colored, semi-transparent layer over selected text that stays in the file when you save and share it. Unlike a physical highlighter, PDF highlights are non-destructive: the original text underneath is untouched and can still be selected, copied, and searched. Every major platform has at least one free way to do this, and none of them require Adobe Acrobat.

How Highlighting Works in PDFs (and One Important Caveat)

When you highlight text in a PDF, the viewer is adding a highlight annotation — a structured object in the PDF file that references the coordinates of the text you selected. This is different from drawing a colored box on top of the page (which is what some basic "markup" tools do). A proper highlight annotation:

• Stays precisely positioned even if the PDF is viewed at different zoom levels
• Allows the text underneath to be searched and copied normally
• Can be removed or edited without affecting the underlying document
• Shows up in the annotations panel of Acrobat, Preview, and most PDF editors

The caveat: highlighting only works on text-based PDFs where the text is real. Scanned PDFs are images, and you can't add a text-aware highlight to an image. If your PDF looks like a photograph of a page, you'll need to run OCR first to create a layer of real text, then highlight. See our OCR guide for the full workflow.

How to Highlight Text in a PDF in Chrome or Edge (Free, Any Device)

Both Chrome and Edge have built-in PDF viewers with basic annotation support, including highlighting. This is the fastest option for quick annotations with no software to install.

In Google Chrome

1. Open the PDF in Chrome (drag it into a Chrome window, or right-click the file and choose Open with → Chrome).
2. Select the text you want to highlight by clicking and dragging.
3. A small toolbar appears above the selection with a highlight icon (a pen/marker). Click it.
4. Choose a color if the option is available. Chrome defaults to yellow.
5. To save the highlights, click the download icon in the top-right toolbar. The saved file includes the highlights embedded in the PDF.

In Microsoft Edge

1. Open the PDF in Edge.
2. Click the Draw or Highlight button in the PDF toolbar at the top of the window.
3. Select your highlight color from the palette.
4. Click and drag over the text to highlight it.
5. Save the file via the save icon or Ctrl+S.

Edge's built-in highlighter offers more color options than Chrome and is slightly more capable for quick annotation work. Both browsers embed the highlights into the file when you save.

How to Highlight Text in a PDF on iPhone and iPad

iOS has built-in PDF annotation through the Markup tool, available in Files, Mail, and Safari without installing anything extra.

Using the Files App

1. Open the Files app and tap the PDF.
2. Tap the Markup icon (pencil in a circle) in the top-right corner.
3. Press and hold on the text you want to highlight, then drag to extend the selection.
4. In the popup menu, tap Highlight.
5. Tap a color swatch to change the highlight color if needed.
6. Tap Done to save. The highlights are embedded in the file.

Using the Notes App

If you've scanned a document into Notes, open the scan, tap the Markup icon, and use the highlighter tool from the toolbar at the bottom. This works well for quick annotations, though exporting a properly annotated PDF from Notes requires tapping the Share icon and choosing Save to Files.

How to Highlight Text in a PDF on Android

Android's default PDF viewer (Google Drive's viewer) doesn't support annotations, so you need a separate app. The best free options:

Adobe Acrobat Reader (Free)

The free version of Adobe Acrobat Reader on Android includes full highlighting support. Download it from the Play Store, open your PDF, tap and hold to select text, and choose Highlight from the context menu. Color options are available in the annotation toolbar. The free version handles highlighting without requiring an Adobe account for basic use.

Xodo PDF Reader (Free)

Xodo is a well-regarded free PDF annotator for Android. Open a PDF, tap the annotation icon in the toolbar, select the Highlight tool, choose a color, and drag across text to apply. Xodo also supports sticky notes, underline, strikethrough, and freehand drawing in the same free tier.

How to Highlight Text in a PDF on Mac

Mac's Preview app — which comes with every Mac at no cost — has full annotation support including multi-color highlighting.

1. Open the PDF in Preview.
2. Select the text you want to highlight.
3. Go to Tools → Annotate → Highlight Text, or press ⌘ + Control + H.
4. To change the color, right-click the highlight and choose a different color from the menu.
5. Save with ⌘S. Preview saves annotations directly into the file.

Preview also lets you add notes (sticky notes), underline, and strikethrough text from the same Annotate menu. For heavier annotation workflows — multiple reviewers, annotation summaries, or exporting comments — you'll want a dedicated PDF editor.

How to Highlight Text in a PDF on Windows

Windows doesn't ship with a PDF annotator the way Mac does with Preview. The built-in Microsoft Edge browser handles basic highlighting (see the browser section above), which covers most use cases.

For a desktop application, the free version of Adobe Acrobat Reader for Windows includes highlighting. Open the PDF, select text, right-click and choose Highlight. Save the annotated file from File → Save.

When You Need More Than Basic Highlighting

For annotation-heavy workflows — reviewing contracts, marking up research papers, collaborating on documents — a full PDF editor gives you more control than browser-based or free viewer tools. UPDF handles highlighting, sticky notes, strikethrough, underline, freehand drawing, stamps, and shape annotations across Windows, Mac, iOS, and Android under a single license. Its annotation summary feature is particularly useful for review workflows: you can export all comments and highlights as a separate summary document rather than having to scroll through the annotated PDF to find each note.

Making Highlights Permanent (Flattening)

By default, PDF highlights are annotations — they can be removed or edited by anyone who opens the file in a PDF editor. If you need the highlights to be permanent (for archiving, legal review, or sharing with someone who might otherwise clear them), you can flatten the PDF to merge all annotations into the page permanently.

Our guide to flattening a PDF covers exactly how to do this and when it makes sense. The short version: once you flatten, the highlights become part of the page image and can no longer be removed or edited without affecting the underlying content.