Linkook is a Python CLI tool for OSINT-driven discovery of linked social media accounts and associated emails across multiple platforms. It takes a single username as input, scans a configurable set of websites (defined in a provider.json file), and recursively extracts linked accounts, usernames, and emails from discovered profiles. The tool supports breach checking via HudsonRock's database or Have I Been Pwned, and can export results to a Neo4j-compatible JSON format for graph visualization. The architecture is modular: a Provider class handles URL templates and regex extraction, a SiteScanner performs HTTP requests and keyword-based existence checks, and a ScannerManager manages concurrent scanning via a thread pool with a queue. The code is well-structured, includes unit tests, and demonstrates solid engineering practices with clean separation of concerns, error handling, and logging.