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Highlights – PDF annotation app for research

It’s the novel approach to PDF annotation that makes this app a cut above the rest

Price: Free to download
Subscription: $3/£3 monthly for Pro
Version: 2020.1.6
Size: 8.3 MB
Seller: Jonas Myren Ribe
Platform: iPhone / iPad / Mac


Call it a bold claim, but Highlights could well be a game-changing app for students and researchers who read, reference, and annotate PDFs using their iPhone, iPad, or Mac. This is because the app takes a new and refreshing approach to PDF annotation which places it a cut above anything else the App Store has to offer.

That novel approach is based on one simple formula. When you annotate PDFs in Highlights, the app parses out the highlighted or annotated content and appends it to a text-based “notes” interface. You can then look back over your PDF’s annotated notes to read through the document’s most important points. It’s a simple idea that has big implications for how we consume PDFs on iPhone, iPad, and Mac alike.

Highlights on iPad.

You can capture content from PDFs via a series of different annotations – either by highlighting them (in a variety of colors), underlining, striking-through, or snapshotting. The way content appears in your PDF’s notes will depend on the annotation used, and as such, this provides a useful way for you to emphasize particular annotations over others. If you need to make a note about something you’ve read, it’s also possible to add comments to selected text.

Adding a comment.

Highlights includes three panes that let you navigate between the app’s various interfaces. There’s the PDF pane, which places the PDF itself centerstage; Notes, which lets you browse through your annotations in a dedicated interface; and finally (and most usefully), a combined PDF and Notes interface, which lets you view your PDF with the annotation notes alongside.

As you’ve probably guessed, the ideal way to use Highlights is on iPadOS – arguably with an Apple Pencil in hand. But Highlights also works a treat on macOS, taking advantage of the cursor, and it can function reasonably well on iPhone (though it does feel quite cramped).

Highlights on macOS.

You can swipe through thumbnails at the bottom of Highlights for iOS and iPadOS to change the page you’re looking at. Disappointingly, though, the app’s palm rejection lets it down in this respect. When resting a palm on the iPad’s screen to annotate a PDF using the Apple Pencil, you’ll often find that this action triggers the page navigation bar. This is something that needs ironing out quickly as it can really interfere with the app’s functionality on iPad.

Highlights on iPhone.

When it comes to sharing, Highlights lets you export either your annotated PDF or your notes. A pro subscription (for $3/£3 per month) lets you export as HTML, TextBundle, or Markdown, as well as the standard PDF option. Highlights Pro also brings table recognition and citation look-ups for students and academics.

Highlights is probably the most interesting PDF annotation app out there. If you regularly handle and annotate PDFs on your iPhone, iPad, or Mac, it could undoubtedly complement your workflow well. Best of all, it’s available to download and use free of charge, with the pro features further enhancing the experience available if you want to dip your toe in further.