Second Brain by Hexact

Second Brain is a local desktop app that gives Claude Desktop persistent memory through MCP. It creates a personal database on your machine where you store contacts, customers, meeting notes, ideas, business data and scraped data. Then Claude reads and writes to it, with your permission, through normal conversation. Ask Claude about a customer and it pulls the answer from your records. Log a meeting and it saves the notes to your database. Look up an article, a competitor, a decision.