Gives Claude persistent memory that survives across sessions and travels between AI tools. You get structured storage for preferences, decisions, and context via a cloud API, with tools to add memories, search semantically, sync local files, and configure your own OpenAI or Anthropic keys for extraction. HippoDid automatically categorizes facts and applies temporal decay so skills stick around while events fade. The Java server connects over stdio and talks to the HippoDid REST API. Useful when you're switching between Claude Desktop, Cursor, and ChatGPT but want the agent to remember what you told it last week without re-explaining your project setup every time.