Carrel walks you through a paper one step at a time, keeps your notes beside the PDF, and brings the paper back later so you remember it. Your notes are plain text files on your computer, and they belong to you.

Get Carrel

1. Open Terminal: press ⌘ Space, type Terminal, and press Return.

2. Paste this line and press Return:

   curl -fsSL radyko.github.io/carrel/install | sh

A minute later Carrel opens. It's now in your Applications folder like any other app: open it from Launchpad, Spotlight or the Dock. There's nothing else to install, and you won't need Terminal again.

Works on macOS (Apple silicon and Intel) and Linux. On Linux it shows up in your applications menu. The same steps are on radyko.github.io/carrel, with a Copy button.

Developers can also run npx radyko/carrel, which needs Node.js.

Update

When there's a new version, Update ready appears at the bottom of the sidebar within about 15 minutes of its release. Click it, then Update. Carrel closes, updates itself, and opens again. Your papers and notes stay exactly as they are. One click always gets the newest version, even if you skipped a few. Running the install line again also updates Carrel.

To see which version you have, open Settings. The version number is under the title.

How it works

1. Add a paper. Drop a PDF on the window, or add one you read on paper.

2. Say why you're reading it. This decides how deep to go.

3. Read in passes. After each one, decide whether to keep going.

   • Survey (5–10 minutes): the big picture.
   • Comprehend (up to an hour): enough to explain it to someone.
   • Reconstruct (a few hours): rebuild it and find its weak spots.

   Stopping after the first pass is normal. Most papers don't need more.

4. Highlight and comment. Select text in the PDF, pick a colour, and write a note beside it.

5. Summarise from memory. Carrel can hide the PDF while you write.

6. Review. After a week, a month and three months, Carrel asks what you remember, then shows what you wrote.

Everything saves as you type. Group papers into collections, such as one per course or project.

Make it yours

In Settings → Look:

• Choose a background tone. Carrel starts on Linen, a warm off-white that is soft on the eyes and tints the PDF pages too.
• Pick an accent colour. Carrel starts on Navy, and the others are deep, quiet colours like slate, old gold and oxblood. Want something louder? The rainbow dot opens a picker for any colour.
• Use Light, Dark, or match your computer.

Your notes

Everything lives in the Carrel folder in your home folder. Each paper gets its own folder holding the PDF and a notes.md file that any text editor can open. There's no account and no cloud. Carrel never deletes your writing. Removing a paper moves it to the Trash.

If something goes wrong

• The install line says the download didn't work: check your internet connection and run it again.
• Your papers seem to be missing after an update: they aren't gone; they are still in the Carrel folder. Quit Carrel completely (⌘Q, or right-click its Dock icon and choose Quit), then open it again. This could happen with updates to version 0.3 or earlier if Carrel was open. Updates now close Carrel properly first.
• Carrel takes a while to open the first time: macOS checks a newly installed app before opening it, which can take a minute on a slower computer. Later opens are quick.
• Anything else: open an issue and say what you did and what you saw.

Uninstall

Move Carrel from Applications to the Trash. On Linux, delete ~/.local/share/carrel. Your notes stay in the Carrel folder until you delete it yourself.

Learn more

• Using Carrel: every feature and keyboard shortcut
• The reading method: where the passes come from and why they work
• Notes and files: the notes format, and how to change the questions
• Development: building and releasing Carrel