Think on paper. Hand it off when it's done.
Sidepaper is a notebook for iPhone, designed for iPhone Duo. You write with your finger, draw boxes and arrows, and talk things through. When the thinking is finished, it turns your page into a short brief for ChatGPT or Claude.
Coming to iPhone. In private TestFlight testing for now. The same boards open on the web: use Sidepaper in your browser.
Start anywhere. Do the thinking on paper.
Bring in a Slack thread or an AI chat, work it out by hand on your phone, and send it back when it's done. Or start on Sidepaper and hand it off whenever you want.
- Slacka thread
- Claudea chat
- ChatGPTa chat
- Cursora spec
- Any MCP app
↓ bring it in at launch↑ send it back now · copy or share
Start where you already are.
Ask Claude, ChatGPT or the assistant in your Slack to put a thread on a Sidepaper page. It lands on your phone as notes you can circle, cross out and write over, and you send it back when you're done.
Or start on a blank page.
Write, sketch and talk it out first. Whenever you're ready, hand it to ChatGPT or Claude with copy or the share sheet.
Either way, what comes back is a set of suggestions you keep or skip, and one tap undoes them all.
Write it the way it comes out.
Box a line and it becomes a card. Draw an arrow and it becomes a link. Circle a few notes to group them. Cross one out and Sidepaper keeps it as something to reconsider instead of throwing it away.
The tidying happens on your phone.
Sidepaper reads your page with a small model we trained for one job: working out what each note is and what goes with what. It runs on the iPhone itself, so it works in airplane mode and your notes stay put.
It learned on practice boards, never on anyone's notes. Everything it does is a suggestion you can skip.
Notes with a date or day are tasks, not constraints.You changed 5 of 5 · learned on this phone
Use thisNot for meUntil it ships, and on older versions of iOS, Sidepaper uses Apple's built-in on-device model.
How you use it
Write by hand.
Your finger is the pen, and it works without a signal. Every stroke is kept exactly as you drew it.
Talk it through.
Talk while you walk. Each thought lands on the page as its own note, and tapping one plays back the moment you said it.
Unfold it.
On iPhone Duo, the folded board is a page you can carry. Open it and it spreads out; close it again and everything stays where you put it.
Pick it up on a computer.
Turn on sync and your boards and ink are on the web too, at sidepaper-web.vercel.app. Keep writing there, search every board, save one as an image or a PDF, or go back to an earlier version.
Share a board.
Invite someone by email from the board and send them the link. They open it on their computer or their iPhone, sign in, and work on the same page with you, or just look if you made it view only. Your photos and recordings stay with you.
When it's done, hand it over.
Tap Done and Sidepaper writes a short brief: these are decisions, not a brainstorm, run with it. Copy or share it into ChatGPT or Claude. Their reply comes back as suggestions. You keep what helps, skip what doesn't, and one step undoes it all.
Done
Status: DONE. I've finished thinking this through. Treat these notes as my final decisions, not a brainstorm.
Run with it: Write the launch plan.
n1 (question): Ship before the Oct 14 code freeze?
n2 (idea): Beta with our 20 biggest customers
n3 (task): Maya drafts the pricing FAQ by Fri
Links I drew:
- n3 depends on n1
Q4 Launch v2
QuestionShip before the Oct 14 code freeze?
IdeaBeta with our 20 biggest customers
TaskMaya drafts the pricing FAQ by Fri
TaskConfirm the freeze date with eng
Applied. 3 changes on your board.
It works with ChatGPT and Claude through copy and paste or the share sheet, so there is nothing to connect and no key to paste. A direct connection is in private testing.
Assistants only ever see the text you pick.
Your photos and voice stay on the phone. Your boards and ink stay there too, unless you turn on sync or share a board, and then they go only to your own account and the people you invite. When you hand something off, only the text of the notes you picked goes.
For people who think with their hands.
- EngineeringThree services, one queue nobody owns, and a retry loop you don't trust.
- ProductNorthwind exports to Excel every Monday. You need to know why before Friday.
- DesignForty-one settings toggles. Ten have to go, and every one must work at the largest text size.
- MarketingA $25k cap, one channel that drove 60% of signups, and one bet left.
- LeadershipTwo bets next quarter, not five. Hire a manager, or grow Aisha?
- AnyoneWho has ever started a prompt with “ok so…”.
Questions
What is Sidepaper?
Sidepaper is a paper notebook for iPhone, designed for iPhone Duo. You write by hand, sketch and talk ideas out, and boxes, arrows, circles and cross-outs become cards, links, groups and challenges. When the thinking is done, you hand a short brief to ChatGPT or Claude and review what comes back.
Why paper instead of typing a prompt?
Because thinking doesn't come out in order. On paper you can box, link, circle and cross out, and Sidepaper keeps that shape when you hand it off, as labeled notes and links instead of one run-on paragraph.
Can I download Sidepaper?
Not on iPhone yet. Sidepaper is in private TestFlight testing and is not on the App Store; it is coming to iPhone, on iOS 18 or later. You can use it on the web now at https://sidepaper-web.vercel.app, signing in with Apple or Google.
Is there a web version?
Yes, at https://sidepaper-web.vercel.app. It has the same boards and most of the same tools: write with a pen or type, talk it through by dictation, tidy, hand off to ChatGPT or Claude, search, export and go back to earlier versions. Turn on sync on the iPhone and your boards and ink show up there too. Photos stay where you added them, and the web never records audio.
Can I share a board with someone?
Yes. Invite them by the email they sign in with, as able to edit or view only, and send them the link yourself; Sidepaper doesn't email anyone. The link works once, for that email, for 7 days. They can open it on a computer or an iPhone. Text, layout and ink are shared; your photos and recordings stay with you.
Does Sidepaper work offline?
Yes. Boards, ink, photos and recordings are stored on your phone, and writing needs no network. You sign in once, the first time you open the app. If you turn on sync, your boards and ink are also kept in your account. Voice transcription runs on the device when your iPhone supports it; if it doesn't, your recordings are kept as they are.
What does Done do?
Done marks a board as finished thinking. The brief it writes tells the assistant to treat your notes as final decisions and run with it: a plan, a write-up, a build or a message. If you edit the board later, Sidepaper shows that it changed since.
Does Sidepaper use AI on the phone?
Yes, for tidying. A small language model we trained for Sidepaper, starting from an open-source base model, works out what each note is and what goes with what. It runs on the iPhone, works offline and never sends your notes anywhere, and it was trained on practice boards, not on anyone's notes. Every change it suggests is yours to keep or skip. It is coming with the launch; until then, and on older versions of iOS, Sidepaper uses Apple's built-in on-device model.
Does Sidepaper send my notes to AI?
Only when you choose to. You hand off the notes you select yourself, by copying or with the share sheet, to the assistant you already use. Only text goes to the assistant; your ink, photos and voice are never sent. Sidepaper uploads your boards only if you turn on sync, and then only to your own account.
Does Sidepaper connect directly to ChatGPT or Claude?
Not yet. Today you paste or share the brief into ChatGPT or Claude, then share or paste the reply back into Sidepaper, which opens it as suggestions for you to review. At launch, Sidepaper will connect to assistants that support MCP, such as Claude and ChatGPT, so they can send you draft boards and pick up boards you have marked Done. You choose which boards they can see, only their text is shared, and replies still come back as suggestions. This connection is in private testing now and isn't open to the public yet.
What happens when an assistant replies?
The reply becomes a list of suggested changes. You keep or skip each one, and the kept changes apply as a single step you can undo. If the board changed after you handed it off, the old reply is rejected instead of being merged blindly.
Who is Sidepaper for?
People who think by writing, sketching and talking: engineers, product managers, designers, marketers and leaders. It runs on iPhone and is designed for iPhone Duo, where the page has room to unfold.