How to Highlight Text in PDF: Free Methods for Every Device

Whether you're studying for an exam, reviewing a contract, or marking up a research paper, highlighting text in a PDF is one of the most common things people need to do with documents. The problem? A lot of people assume you need paid software like Adobe Acrobat Pro to do it. You don't. Here's how to highlight PDFs for free on every device you own.

Why Highlight PDFs?

Highlighting isn't just about making things look colorful. It serves real purposes:

  • Study and research — Mark key passages for quick review later
  • Legal review — Flag important clauses in contracts and agreements
  • Collaboration — Draw attention to specific sections when sharing documents with a team
  • Personal reference — Bookmark important information in manuals and guides

Whatever your reason, the methods below will get the job done without costing you a cent.

How to Highlight PDFs on Windows (Free)

Using Microsoft Edge (Built-In)

If you're on Windows, you already have a PDF highlighter built into your browser. Microsoft Edge has a solid PDF annotation tool:

  1. Open the PDF file in Microsoft Edge (right-click the file and choose "Open with Edge")
  2. Click the Highlight button in the toolbar at the top (it looks like a marker pen)
  3. Select the text you want to highlight by clicking and dragging
  4. Choose your highlight color from the available options
  5. Save the file (Ctrl+S) — the highlights are saved directly in the PDF

Edge also supports adding text notes and drawing on PDFs. It's genuinely one of the best free PDF annotation tools on Windows, and most people don't even know it exists.

Using Xodo PDF Reader

Xodo is a free PDF reader that offers more annotation features than Edge:

  1. Download and install Xodo PDF Reader from the Microsoft Store or xodo.com
  2. Open your PDF in Xodo
  3. Select the Highlight tool from the toolbar
  4. Click and drag over the text you want to highlight
  5. Right-click the highlight to change its color or add a comment
  6. Save the annotated PDF

How to Highlight PDFs on Mac (Free)

Using Preview (Built-In)

Mac users have it easy. The built-in Preview app has PDF highlighting built right in:

  1. Open the PDF in Preview (it's the default PDF viewer on Mac)
  2. Click the Markup Toolbar button (pen icon near the top right)
  3. Click the Highlight tool (marker icon)
  4. Select the text you want to highlight
  5. Click the down arrow next to the highlight tool to change colors (yellow, green, blue, pink, purple)
  6. Save the file (Cmd+S)

Preview is fast, lightweight, and handles highlighting perfectly. You can also add text boxes, shapes, signatures, and notes in the same toolbar. For most Mac users, there's no need to install anything extra.

How to Highlight PDFs on iPhone and iPad

Using Apple Books

If you open a PDF in Apple Books, you can highlight text directly:

  1. Open the PDF in Apple Books (share the file and choose Books)
  2. Tap and hold on the text you want to highlight
  3. Drag the selection handles to cover the text range
  4. Tap Highlight from the pop-up menu
  5. Choose a color from the options that appear

Using the Files App

On newer versions of iOS, the Files app supports PDF markup directly:

  1. Open the PDF in the Files app
  2. Tap the Markup button (pen icon at the top)
  3. Use the highlight tool to select and mark text
  4. Tap Done to save your changes

How to Highlight PDFs on Android

Using Google Drive

Most Android phones come with Google Drive pre-installed, which includes PDF annotation:

  1. Open the PDF in Google Drive
  2. Tap the three-dot menu and select "Open with" then "Google Drive PDF Viewer"
  3. Tap the Edit icon (pen) at the bottom
  4. Select the Highlight tool and drag over text
  5. Save the changes

Using Xodo (Android)

Xodo's Android app is one of the best free PDF annotation tools on mobile:

  1. Install Xodo from the Google Play Store
  2. Open your PDF in Xodo
  3. Tap the Highlight icon in the toolbar
  4. Swipe across the text you want to highlight
  5. Tap a highlight to change its color or add a note
  6. Save or share the annotated PDF

How to Highlight PDFs Online (No Installation)

Don't want to install anything? Several browser-based tools let you highlight PDFs directly in your web browser:

  • Xodo Online — Full-featured PDF editor in your browser with highlighting, comments, and drawing tools
  • PDFescape — Free online PDF editor with highlight and annotation tools
  • Sejda PDF Editor — Clean interface with highlighting, text editing, and form filling
  • Canva PDF Editor — Good for visual documents with highlighting and markup tools

For online tools, keep privacy in mind. If your document contains sensitive information, consider using a browser-based tool that processes files locally rather than uploading them to a server.

Tips for Effective PDF Highlighting

Whether you're studying, reviewing, or collaborating, these tips will help you get more out of PDF highlighting:

  • Use colors consistently — Yellow for important facts, green for definitions, pink for questions, blue for key quotes
  • Don't over-highlight — If everything is highlighted, nothing stands out. Aim for 10-15% of the text
  • Add comments to highlights — Attach notes explaining why you highlighted something
  • Use strikethrough for deletions — When reviewing documents, strikethrough is better than highlight for text you want removed
  • Export your highlights — Many tools let you export a summary of all highlighted text for quick reference

Common Highlighting Problems and Fixes

Can't select text? — The PDF might be a scanned image rather than real text. You'll need OCR (Optical Character Recognition) to make the text selectable first.

Highlights won't save? — Some PDFs have security restrictions that prevent annotations. You may need to remove the restrictions first, or use "Print to PDF" to create an unrestricted copy.

Wrong highlight color? — Most tools let you right-click (or long-press on mobile) an existing highlight to change its color after the fact.

Highlight tool missing? — Not all PDF viewers support highlighting. If the tool isn't there, switch to one of the readers mentioned above.

Which Tool Should You Use?

Here's a quick decision guide based on your situation:

  • Quick highlight on Windows — Microsoft Edge (already installed)
  • Quick highlight on Mac — Preview (already installed)
  • On iPhone — Apple Books or Files app
  • On Android — Xodo or Google Drive
  • No installation wanted — Xodo Online or Sejda
  • Need collaboration features — Xodo (shared annotations)
  • Privacy-sensitive documents — Use a local tool, not online

The bottom line: you don't need to pay for Adobe Acrobat to highlight PDFs. Free tools on every platform handle this just fine. Pick the one that's already on your device and start highlighting.

Need to work with PDFs?

Try PeacefulPDF's free online tools: