Second Brain is an AI memory companion for iOS that models how your mind actually works. Capture thoughts by text or voice. AI classifies each memory into three layers — instant, short-term, and long-term — extracts tags, and generates summaries. No folders, no manual sorting. Ask questions like "What did Sarah say last week?" and get answers from your own memories via semantic search. Weekly AI reflections find patterns in your thinking you missed. Free with limits, Pro at $4.99/mo.