Signed search keys in Elastic App Search offer a sophisticated way to personalize a user's search experience by embedding specific filters and boosts into the search keys, ensuring tailored and relevant results for each user. These keys are JSON Web Tokens signed with an API key and allow for direct searches via the App Search API, bypassing the need for backend processing to enforce search options. In practical applications, such as a marketplace, signed search keys can be used to filter out draft items, boost categories of interest based on user history, and control visibility of certain fields for unauthenticated users, enhancing user-specific content delivery. This functionality provides a powerful tool for creating a customized search experience, as demonstrated in various examples and a demo, while also being accessible for experimentation through a free trial of Elastic Cloud.