This Mac app is essential if you read a lot of PDFs

Screenshots of the Highlights app from the Apple App Store.
The Highlights app provides you with the best way to comb through lots of research in PDFs. (Image credit: Apple App Store / Highlights App)
Highlights: PDF Reader & Notes

The Highlights PDF logo from the Apple App Store

(Image credit: Apple App Store/Highlights PDF Reader and Notes)

Mac / iPhone / iPad - Free (In-app purchases) 

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Back in 2020 I wrote a book that involved huge amounts of research. It was during the first lockdown so this research didn't look like trips to a library or in-person interviews. Instead, it was all conducted via the internet and many, many copies of surveys, studies and research papers. 

The majority of these documents were PDFs and I found them really difficult to markup and organize. I only wish I had discovered Highlights back then, an app that works on your iPhone and iPad, but I highly recommend using it on your Mac for the best reading experience. 

The Highlights app does a lot of things, but one of the simplest and yet most useful features is that you can use it to highlight and markup any text and images in a PDF that are then formatted into notes on the fly. It can also extract notes from any existing PDFs as soon as you open them up. Research tasks are about to get a whole lot more straightforward. 

Make PDF research quicker and easier

When you open Highlights, you'll see a toolbar — this is the main hub of the app. It contains thumbnails to documents, annotation and markup tools and notes, all in one place. This enables you to really quickly and easily move between different documents and all of the notes you've been making across them.

It's very easy to annotate a PDF, just drag your pointer or finger over the bit you want to markup and a pop-up appears that allows you to copy, underline, highlight and lookup text or add it to a note. Highlights also works with images and is optimized for scientific research, so that includes graphs, charts and any other sorts of diagrams too, all of which can be added to a note along with text. 

Once you've created lots of notes from your PDFs you can export them anywhere as PDF files themselves. If you get the Highlights Pro version you can export notes in editable formats too, like Markdown and HTML. The Pro app costs $3.99/£3.99 monthly and $29.99/£29.99 a year and comes with more extra features, like custom default colors for different annotation tools and integration with reference managers. 

If you're doing a lot of research and writing it up for a paper, a study, a book or anything else, I'd also recommend checking out some of the best comprehensive writing apps. My favorite, and the one I used to write my book is Scrivener


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Becca Caddy

Becca Caddy is a contributor to iMore, as well as a freelance journalist and author. She’s been writing about consumer tech and popular science for more than a decade, covering all kinds of topics, including why robots have eyes and whether we’ll experience the overview effect one day. She’s particularly interested in VR/AR, wearables, digital health, space tech and chatting to experts and academics about the future. She’s contributed to TechRadar, T3, Wired, New Scientist, The Guardian, Inverse and many more. Her first book, Screen Time, came out in January 2021 with Bonnier Books. She loves science-fiction, brutalist architecture, and spending too much time floating through space in virtual reality. Last time she checked, she still holds a Guinness World Record alongside iMore Editor in Chief Gerald Lynch for playing the largest game of Tetris ever made, too.