Four progressively improved approaches to concurrent programming in Go, demonstrated through a URL health checker. Covers synchronous iteration, goroutines with a naive sleep workaround, WaitGroup-based synchronization from the sync package, and typed channels for structured goroutine communication — illustrating Go’s concurrency model from basic to idiomatic.

Step-by-step tutorial for building a REST API server in Go using the httprouter multiplexer. Covers creating endpoints, structuring the project across multiple files, writing tests with the httptest package, and adding middleware for logging — finishing with a recommended package layout for larger projects.