Cairn: Your Second Brain
Dump it. Cairn remembers.
Free · In‑App Purchases
Not a journal. Not a notes app. A second brain: dump any thought in two seconds and Cairn brings it back when it matters. All the AI runs on your iPhone.
Cairn is a second brain for every random thought.
The idea in the shower. The thing you promised to do. The name of that book. Dump it into Cairn in seconds and let your head go quiet. Cairn keeps it, understands it, and brings it back when it matters. No account. No cloud AI. Your thoughts never leave your iPhone.
Use it however your brain works: ideas, plans, reminders, to-dos, things to remember, or the occasional 2am thought. No folders, no formatting, no rules.
DUMP IT
• Type, dictate or take a photo. Voice is transcribed on your device
• Add a reminder that rings like an alarm, or pin the place you were
• Home Screen widget, Siri Shortcuts and the Share sheet, so nothing slips away
• Your own filters for ideas, plans, a morning to-do, anything
FIND IT BY MEANING, NOT EXACT WORDS
• Type "trouble sleeping" and find "can't sleep again"
• Search by date: "last March", "June 2024", "this week"
• Photos are searchable too. Cairn reads the text in them and knows what they show
• Search with your voice
• Optional: find your thoughts from iPhone Search
CAIRN REMEMBERS, SO YOU DON'T HAVE TO
• Echoes: write something you thought months ago, and Cairn shows you the first time
• Open loops: plans you wrote down and never closed, brought back gently
• On this day: what was on your mind a year ago today
• One card a day, never more. Tap "Not useful" and you'll see less of it
SEE YOUR MIND
• List or Sky: every thought is a star, and related thoughts connect on their own
• Today: build a cairn, a stone for every day you dump a thought
• Your thinking archetype and the themes that keep coming back
• A calendar of your days. Go back to any date in one tap
• With Apple Intelligence, themes get names and answers read naturally, always from your own words, never made up
PRIVATE BY DESIGN
• Everything runs on your device: understanding, search, transcription, photo reading
• No account, no sign-in, no ads, no tracking. Your thoughts stay on your device, and backups go only to your own iCloud
• Face ID app lock
• Free encrypted backup to your own iCloud Drive, and an encrypted export you keep
• Nothing is ever deleted on a timer
FREE, AND CAIRN+ ONCE
Capture, search, the Sky, photos, voice, reminders, On this day and backup are free forever.
Cairn+ adds Echoes, Open loops, insights and your archetype, your own filters and extra themes. Every new user gets all of Cairn+ free for 14 days, no card, nothing to cancel. After that, Cairn+ is one payment, yours for good. No subscription.
Works on iPhone and iPad.
Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Privacy: https://shreypinnada.github.io/cairn-legal/privacy-policy-ios.html
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Cairn has a new name: Your Second Brain.
It was never meant to be a diary. Cairn is where you put anything you don't want to forget: an idea in the shower, a hidden spot you found on a trip, a friend's birthday, something you promised to do. Dump it in seconds, set a reminder if you like, and Cairn remembers it for you.
Everything still runs privately on your iPhone.
The developer, Shrey Pinnada, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Purchases
- Location
- Identifiers
- Usage Data
- Diagnostics
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Shrey Pinnada
- Size
- 19 MB
- Category
- Productivity
- Compatibility
Requires iOS 18.0 or later.
- iPhone
Requires iOS 18.0 or later. - iPad
Requires iPadOS 18.0 or later.
- iPhone
- Languages
- English
- Age Rating
9+
- 9+
- Contains
Health or Wellness Topics
- In-App Purchases
Yes
- Cairn+ Lifetime $14.99
- Copyright
- © 2026 Pinnadas
