Highlight a confusing word, name, or equation in a textbook, paper, or lecture slide, then click Doe 
. A clear explanation appears right beside it, written for what you’re reading and backed by sources you can check.
Chapter 3 · Thinking at the margin
Halfway through a bad film, most of us stay in our seats. Economists have a name for that pull: the sunk cost fallacy. The ticket is paid for either way, yet walking out still feels like wasting it.
Why Doe
Looking something up usually means a new tab, a page of search results, and a definition that doesn’t match your class. Doe explains it right where you are.
The same word can mean different things in different classes. Doe reads the paragraph around your highlight, so you get the meaning that fits.
In an economics textbook
Depression
A long, severe drop in economic activity, deeper and longer lasting than a recession.
In a psychology reading
Depression
A mood disorder marked by lasting sadness and loss of interest that gets in the way of daily life.
No new tabs, no copying into a chatbot, no explaining what class it’s for. The card opens beside your page and closes when you click away.
Every explanation is based on sources you can open. When a detail about a person, book, or event isn’t backed up, Doe tells you.
Each topic gets the views that help most.
A scientist
Marie Curie
ContributionsLife & Context
An idea
Opportunity cost
ELI5Breakdown
A formula
F = ma
SymbolsIntuition
Ask a follow up question, open a related idea, or step back with ⌘[. Every lookup is saved on your Mac, so you can review them before an exam.
How it works
A word, a name, or an equation, in a website, a PDF, or your notes. Nothing to highlight? Type a topic instead.
Step 2Doe sits on your screen as a little croissant. Prefer the keyboard? Press ⇧⌘L instead.
Get the idea in a few lines. Ask a follow up question, open a related idea, or click away to get back to reading.
Uses
From the first week of class to your first week at work.
Key terms explained the way your class uses them.
Try highlighting opportunity cost
Jargon, methods, and the people a paper cites.
Try highlighting p value
Make sense of the shorthand on slides and PDFs from class.
Try highlighting ATP synthase
What each symbol in a formula means, and why it works.
Try highlighting PV = nRT
Background on unfamiliar names, places, and events.
Try highlighting Treaty of Versailles
Get up to speed on the terms of a field that’s new to you.
Try highlighting EBITDA
FAQ
Want to see what changed in the latest version? Every update has notes on the releases page.
See what’s newDoe is free during early access. You don’t need an account or a credit card to use it.
You don’t have to copy, paste, or explain what you’re reading. Doe sees the paragraph around your highlight, looks up sources on the web, and explains the term the way that page uses it, in a small card beside your reading.
Each explanation is based on sources found for that topic, and you can open them from the card. For people, books, and events, Doe also lists any details the sources don’t back up. AI can still make mistakes, so check anything important before you rely on it.
Doe explains what you’re reading. It isn’t built to write essays or solve assignments for you. Check your course’s rules on AI tools, and cite the original sources rather than the card.
Almost anywhere you can highlight text on your Mac: websites in Safari or Chrome, PDFs in Preview, Notes, and most document apps. If nothing is highlighted, you can type a topic instead.
Yes. Highlight a formula to see it written out clearly, what each symbol means, and the intuition behind it. It reads equations on many websites. If it can’t read one reliably, it tells you instead of guessing.
That’s Doe. Highlight something and click the croissant, and the explanation opens right next to it. Drag it anywhere you like. If you’d rather keep your screen clear, choose Hide Doe from the menu bar and press ⇧⌘L instead.
That’s the Mac setting that lets an app see what you’ve highlighted in other apps. Doe only looks when you ask it to, by clicking the croissant or pressing ⇧⌘L. You can still type a topic without it.
To write the explanation, your highlight and a little of the text around it are sent to the AI service that writes the card, and the term is used for a web search. Nothing is tied to an account. Your history stays on your Mac, and the surrounding text is never saved.
Google’s Gemini, by default. If you already have an account with OpenAI, Groq, Cerebras, or Inception, you can connect it in Settings instead.
Any Mac running macOS 14 Sonoma or later, with an Apple or Intel chip. To check yours, open the Apple menu and choose About This Mac. You’ll need an internet connection, and the app keeps itself up to date.
Free during early access. No account needed. To remove it, drag it to the Trash.
Download for MacVersion 1.4.0 · macOS 14 or later