Pen Buddy for Mac

A Mac study app, with a tutor one shortcut away.

Notes, maths, code and PDFs in a calm, native Mac app. Press ⇧⌘Space in any app and talk it through; share your screen and Buddy follows along.

Press ⇧⌘Space from any app
Follows your screen when you share it
Live maths and code in your notes

All Notes

Naming Organic Compounds11:02 AMFind the longest carbon chain… Note

The Chain Rule10:55 AMWhen one function sits inside… Note

Exam Plan — Week 610:29 AMChain rule practice set Note

Two Pointers12:56 AMOn a sorted array, walk one p… Note

Black–Scholes11:02 AMN(d2): the risk-neutral chance… Note

Binary Search11:02 AMdef lowerbound(nums, target): Note

Coin Change11:02 AMFewest coins that make up am… Note

Integration by Parts10:29 AMPick u with LIATE — the first o… Note

October 7, 2026 at 10:55 AM

NoteSessionsBrief

#The Chain Rule

When one function sits inside another, differentiate the outside, keep the inside, then multiply by the derivative of the inside.

\frac{d}{dx}f(g(x)) = f'(g(x))\cdot g'(x)

Worked examples

\frac{d}{dx}\sin(x^2) = \cos(x^2)\cdot 2x

\frac{d}{dx}(3x+1)^5 = 15(3x+1)^4

Talk to Buddy⇧⌘Space

Press one button and talk. Buddy answers out loud, with live captions, and stops when you cut in.

How it works

A calm notebook, with a friend one shortcut away.

A native Mac app with live maths and code, and Buddy one shortcut away in any app.

Everything in one notebook.

Your notes, problems, PDFs and every study session, in one place. Maths and code render as you type.

Just you and the page.

When you want to focus, the sidebar and the list fold away.

Press ⇧⌘Space from any app

Press one button and talk.

Buddy answers out loud, with live captions. Interrupt it and it stops. Add a thought while it answers, and it answers once.

Just ask. It writes it in.

Ask Buddy to add something to your notes and it writes it into the note you have open, in the right place. One tap to undo.

All Notes

Naming Organic Compounds11:02 AMFind the longest carbon chain… Note

The Chain Rule10:55 AMWhen one function sits inside… Note

Exam Plan — Week 610:29 AMChain rule practice set Note

Two Pointers12:56 AMOn a sorted array, walk one p… Note

Black–Scholes11:02 AMN(d2): the risk-neutral chance… Note

Binary Search11:02 AMdef lowerbound(nums, target): Note

Coin Change11:02 AMFewest coins that make up am… Note

Integration by Parts10:29 AMPick u with LIATE — the first o… Note

October 7, 2026 at 10:55 AM

NoteSessionsBrief

#The Chain Rule

When one function sits inside another, differentiate the outside, keep the inside, then multiply by the derivative of the inside.

\frac{d}{dx}f(g(x)) = f'(g(x))\cdot g'(x)

Worked examples

\frac{d}{dx}\sin(x^2) = \cos(x^2)\cdot 2x

\frac{d}{dx}(3x+1)^5 = 15(3x+1)^4

All Notes

Naming Organic Compounds11:02 AMFind the longest carbon chain… Note

The Chain Rule10:55 AMWhen one function sits inside… Note

Exam Plan — Week 610:29 AMChain rule practice set Note

Two Pointers12:56 AMOn a sorted array, walk one p… Note

Black–Scholes11:02 AMN(d2): the risk-neutral chance… Note

Binary Search11:02 AMdef lowerbound(nums, target): Note

Coin Change11:02 AMFewest coins that make up am… Note

Integration by Parts10:29 AMPick u with LIATE — the first o… Note

October 7, 2026 at 10:55 AM

NoteSessionsBrief

#The Chain Rule

When one function sits inside another, differentiate the outside, keep the inside, then multiply by the derivative of the inside.

\frac{d}{dx}f(g(x)) = f'(g(x))\cdot g'(x)

Worked examples

\frac{d}{dx}\sin(x^2) = \cos(x^2)\cdot 2x

\frac{d}{dx}(3x+1)^5 = 15(3x+1)^4

All Notes

Naming Organic Compounds11:02 AMFind the longest carbon chain… Note

The Chain Rule10:55 AMWhen one function sits inside… Note

Exam Plan — Week 610:29 AMChain rule practice set Note

Two Pointers12:56 AMOn a sorted array, walk one p… Note

Black–Scholes11:02 AMN(d2): the risk-neutral chance… Note

Binary Search11:02 AMdef lowerbound(nums, target): Note

Coin Change11:02 AMFewest coins that make up am… Note

Integration by Parts10:29 AMPick u with LIATE — the first o… Note

October 7, 2026 at 10:55 AM

NoteSessionsBrief

#The Chain Rule

When one function sits inside another, differentiate the outside, keep the inside, then multiply by the derivative of the inside.

\frac{d}{dx}f(g(x)) = f'(g(x))\cdot g'(x)

Worked examples

\frac{d}{dx}\sin(x^2) = \cos(x^2)\cdot 2x

\frac{d}{dx}(3x+1)^5 = 15(3x+1)^4

Talk to Buddy⇧⌘Space

All Notes

Naming Organic Compounds11:02 AMFind the longest carbon chain… Note

Derivatives11:40 AMRates of change, and the rules… Note

The Chain Rule10:55 AMWhen one function sits inside… Note

Exam Plan — Week 610:29 AMChain rule practice set Note

Two Pointers12:56 AMOn a sorted array, walk one p… Note

Black–Scholes11:02 AMN(d2): the risk-neutral chance… Note

Binary Search11:02 AMdef lowerbound(nums, target): Note

Coin Change11:02 AMFewest coins that make up am… Note

October 7, 2026 at 11:40 AM

NoteSessionsBrief

#Derivatives

Rates of change, and the rules that make them quick.

Rules

Power rule: $\frac{d}{dx}x^n = nx^{n-1}$
Product rule: $(uv)' = u'v + uv'$

Examples

\frac{d}{dx}\,3x^4 = 12x^3

Practice

Problems 1–8
Review the product rule

Talk to Buddy⇧⌘Space

How it helps

It helps you learn. It won’t do it for you.

Buddy works the problem out quietly in the background, then gives you the smallest help that gets you moving again.

How do you want to work?

Talk it through together, or have a go on your own first.

A nudge

A question that points you the right way, from hints Buddy prepared in the background.

Point at the spot

The exact line on your page, or in your code.

Explain the idea

On a card or a diagram, not a lecture.

The full solution

Only when you ask for it.

Privacy

Your notebook, your device.

Your notes live on your Mac or iPad. Pen Buddy sends AI services only what it needs to think, and only when it needs it.

Stays on your device

Your notes, handwriting and PDFs
Study sessions and review cards
Reading your handwriting and the text on your screen

Sent when Buddy needs it

Your speech, to turn it into text (Amazon Transcribe)
The conversation and what Buddy needs to read (Google Gemini, Amazon Bedrock as backup)
A screen image or page text, only when there’s something new to read

Automatic screen reads are never recorded or saved. While Buddy can see your screen, a “Screen shared” badge is always showing, with a stop button.

FAQ

Questions, answered.

Is Pen Buddy a native Mac app?

Yes. Pen Buddy is a native study notebook for the Mac, with live maths and code in your notes, your PDFs and every study session in one place, and Buddy, a tutor you talk to, one shortcut away.

How do I talk to Buddy while I’m in another app?

Press ⇧⌘Space from any app and talk. Buddy answers out loud with live captions, in a sentence or two. Interrupt it and it stops.

Can it help with what’s on my screen?

Yes, when you share it. Share your screen once for the conversation, and Buddy follows the page you’re on: a problem in your browser, your code and its test runs, a PDF or a reading. A “Screen shared” badge with a stop button is always showing.

Which apps does it work with?

Whatever you study in. Buddy follows the screen you share, so it works alongside your browser, your code editor, your PDF reader and your notes.

Is it a good note-taking app for studying?

It’s built for it. Maths and code render as you type, PDFs sit next to your notes, the sidebar folds away when you want to focus, and every session with Buddy is written into the note you have open, with review questions for later.

Can I import my Apple Notes?

Yes. On the Mac, Import Notes brings in Apple Notes, as well as GoodNotes and Notability exports, PDFs, images, Markdown and HTML. Any note exports as Markdown.

Which Macs does it run on?

Macs with Apple silicon (M1 or later) running macOS 14 or later. The download goes live on this site at launch.

Does it work offline?

Your notebook does, and your notes are stored on your Mac. Talking to Buddy needs a connection, because its thinking runs on AI services.

Pen Buddy

Everything you need to study, and someone to study with.