Second Brain — AI Memory Companion for iOS

What is Second Brain?

An AI memory companion for iOS, by Smart Kiitös Oy

Second Brain is an AI memory companion app for iOS, built by Smart Kiitös Oy in Finland. It captures your thoughts the moment they arrive — by text or voice — and uses on-device Apple Foundation Models together with the Anthropic Claude API (Haiku for exploration, Sonnet for reflections) to classify, connect, and recall them when you need them most. A three-layer memory system inspired by neuroscience moves notes from Instant to Short-term to Long-term storage, so quick fragments and lasting ideas each get their own home. Everything lives locally in SwiftData, with optional iCloud sync via your private CloudKit container — no analytics, no third-party servers, no training on your data. The free tier includes 10 captures and 3 explores per day; Second Brain Pro unlocks unlimited use for $4.99/month or $39.99/year.

Features

What features does Second Brain have?

Capture everything, forget nothing. Second Brain organizes your thoughts with AI so you can focus on what matters.

AI Classification

Capture a thought and AI instantly classifies it — identifying the memory type, extracting tags, and generating a summary. All on-device, zero API cost.

Voice Capture

Press and hold to record. Real-time transcription fills your capture field with live waveform feedback. Supports multiple languages.

Explore Memory

Ask questions about your memories. Hybrid recall finds related memories through people, text, and semantic similarity — then AI synthesizes insights across them.

Weekly Reflections

AI reviews your memories on a schedule — daily processing, weekly theme analysis, and monthly deep reflections that reveal growth patterns in your thinking.

Memory Graph

See how your ideas connect. A force-directed graph visualizes relationships between memories based on semantic similarity and shared tags.

People Cards

Create cards for the people in your life. AI detects names in your memories and links them automatically — so you remember everything about everyone.

How It Works

How does Second Brain's memory system work?

Second Brain models the three-layer human memory system. Capture fragments of information and let AI classify, link, reflect, and surface the right memory at the right time.

⚡ Instant

Fleeting Thoughts

Quick fragments, daily observations, things that pop into your head. AI processes these daily — upgrading the important ones and archiving the rest.

"Great coffee place on Mannerheimintie"

"Check if the meeting was moved"

🔄 Short-term

Active Context

Goals, deadlines, project notes, and plans for the near future. These stay active for the week and feed into your weekly reflections.

"Prepare slides for Friday's presentation"

"Lisa mentioned she's moving to Berlin"

💎 Long-term

Core Knowledge

Important experiences, values, life philosophies, and key relationships. These are your permanent memories — strengthened over time through reflection.

"My approach to difficult conversations"

"Career goal: build products that matter"

Privacy First

🔒 Your memories stay yours

Second Brain is built with privacy at its core. Your data lives on your device — not on our servers, not in a database we control.

📱

Local-First Storage

All memories stored on-device with SwiftData. Your data never leaves your phone unless you choose iCloud sync.

🚫

No Server Collection

Zero data collected via our servers. No analytics, no tracking, no user profiles built from your memories.

✈️

Works Offline

Core features work without internet. On-device AI classification runs locally with zero API cost.

☁️

Optional iCloud Sync

Pro users can opt into iCloud sync via CloudKit for cross-device access. Fully encrypted, fully optional.

Read our full Privacy Policy

Pricing

How much does Second Brain cost?

Second Brain is free to use with generous limits. Go Pro for unlimited capture, deeper AI insights, and powerful features.

Free

Free forever

10 memory captures / day
AI classification (on-device)
3 memory explorations / day
3 people cards
Memory connection graph
Theme discovery
Weekly reflections
Data export

Pro

$4.99 / month

or $39.99 / year (save 33%) · 3-day free trial

Unlimited memory captures
AI classification (on-device)
20 memory explorations / day
Unlimited people cards
Memory connection graph
Theme discovery
Deep weekly & monthly reflections
Data export & iCloud sync

FAQ

Frequently asked questions

Common questions about Second Brain.

What is Second Brain and who is it for?

Second Brain is an iOS app that captures and recalls your thoughts using AI. It's built for writers, researchers, designers, founders, and anyone who has more ideas than they can hold in their head — people who want to think out loud without losing what they said.

How does Second Brain protect my privacy?

All notes are stored locally in SwiftData on your device. Sync, when enabled, runs through your own private iCloud CloudKit container. We operate no servers that store your content, run no analytics, and never use your data to train AI models.

Which AI models does Second Brain use?

Second Brain uses Apple Foundation Models on-device for instant classification (zero API cost), and the Anthropic Claude API for cloud features: Claude Haiku powers fast Explore queries and Claude Sonnet generates deeper weekly reflections.

What is the three-layer memory system?

Inspired by how human memory works, captures flow through three layers: Instant (just-arrived raw thoughts), Short-term (recent notes still being shaped), and Long-term (consolidated, searchable knowledge). The app handles promotion automatically based on how you interact with each note.

How much does Second Brain Pro cost?

Second Brain is free with 10 captures and 3 AI explores per day. Pro removes those limits and unlocks weekly reflections for $4.99 per month or $39.99 per year, billed through the App Store.

Does Second Brain work offline?

Yes. Capturing notes, browsing memories, and on-device classification all work offline. Cloud-powered features (Explore queries, weekly reflections) require an internet connection because they call the Claude API.

Think less, remember more

See Second Brain in action