This is a production-grade favicon finder and icon server built in Go. It provides an HTTP API that, given a website URL, fetches the page, extracts all icon links (favicon, apple-touch-icon, etc.), downloads them in parallel, decodes dimensions, and returns the best matching icon. It also generates fallback letter icons using embedded fonts when no icon is found. The service includes SSRF protection, configurable caching via groupcache, Prometheus metrics, and CORS support. The project is structured as a monorepo with a core library (`besticon`), a web server (`iconserver`), and several reusable standalone packages for ICO parsing (`ico`), dominant color extraction (`colorfinder`), letter icon generation (`lettericon`), and a VCR-based HTTP test recorder (`vcr`). The architecture demonstrates good separation of concerns and hardened HTTP networking. It is primarily an application (HTTP service and CLI) with strong data engineering aspects in image processing and testing infrastructure.