Isy.AI vs Cairn
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Isy.AI
Capture thoughts, voice memos, images, and PDFs, and let AI automatically link them to related past ideas. Engage in conversations with your notes, receive daily digests of connected thoughts, and visualize your knowledge network.
- Automatic note linking and connection
- Text, voice, image, and PDF capture
- AI-powered chat with your notes
- Daily digests of connected ideas
- Visual knowledge map
- Export notes as Markdown or PDF
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Write it down. Isy remembers how it connects. Type or talk: a thought on a walk, a line worth keeping, half an idea before sleep. Isy files it, links it to what you thought months ago, and brings it back when it matters. No folders. No manual links. CAPTURE IN SECONDS • Type a note, record your voice, or upload an audio file • Brain dump: talk through everything on your mind and Isy turns each idea into its own note • Turn screenshots, photos, whiteboards and slides into notes • Upload a PDF and keep the concrete ideas that belong in your notebook • Bring in what another AI assistant already knows about you with one prompt ISY CONNECTS IT • Every note is tagged and linked to related earlier notes automatically • A private feed surfaces complete, standalone connections from across your notes • Flip a card for the full read, add a follow-up thought, or continue it in Chat • Hide a connection once and Isy will not bring back that card or a close restatement • The Isy map shows your Areas at a glance and how closely they connect THINK WITH WHAT YOU KNOW • Chat with your notes: answers cite the notes they come from and say so when your notes do not cover something • Tap a paragraph in an answer to save it as a note • A daily digest resurfaces older ideas that connect to what is active now • Optional reminders for new connections and your daily digest EVERYWHERE YOU SIGN IN • Sign in with Apple or Google for a free account: the same notebook on your iPhone and on the web at isy-ai.app • Share a note, digest, connection, map or chat as a clean PDF • Export everything as Markdown at any time • Lock Isy with Face ID TWO WAYS TO USE ISY • With a free account: your notes on every device, and all of Isy's AI • Without an account: a simple notebook on your iPhone. Nothing leaves it, and there are no AI features YOUR NOTES STAY YOURS Your notes are encrypted in transit and at rest. Isy's AI runs through Isy Cloud with Google (Gemini) and Groq, and neither trains AI on your notes. Your notes are never sold and never used for ads. Delete your account any time from Settings. Privacy policy: isy-ai.app/privacy Questions or ideas: support@isy-ai.app
Cairn
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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
Screenshots
Verdict
The clearest difference is in-app purchases: Isy.AI at none against Cairn's 1. Isy.AI also leads on iOS requirement (16.4 vs 18.0). On price, update cadence, ads and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Cairn sells 1 one-off in-app purchase. Isy.AI asks for nothing beyond the download.
Both ship on a similar rhythm, roughly every 3 days. Both last shipped on October 31, 2026.
| Parameter | Isy.AI | Cairn |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (2 ratings) — better | — |
| Number of ratings | 2 — better | — |
| Update frequency | Every 3 days | Every 3 days |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free | — |
| Devices | iPhone | iPhone, iPad — better |
| Requires iOS | 16.4 — better | 18.0 |
| Further details — not scored | ||
| Size | 60 MB | 18 MB |
| Age rating | 17+ | 4+ |
| Developer | Akhil Arunkumar | Shrey Pinnada |
In-app purchases
Isy.AI
No in-app purchases
Cairn
- Cairn+ Lifetime$14.99









