Is main.go Required in a Go Project?

`main.go` is not mandatory — it’s just a common convention. what *is* required for an executable go program is a `main` package containing a `func main()` entry point, regardless of the filename.

In Go, the build and execution system doesn’t enforce any specific filename — only structural and naming requirements at the package and function level. As long as your source file declares package main and defines a func main() with no arguments and no return values, go run, go build, or go install will treat it as an executable program.

For example, this file named api-server.go is perfectly valid:

package main  import (     "fmt"     "net/http" )  func main() {     http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {         fmt.Fprintf(w, "Hello from Go API!")     })     fmt.Println("API server starting on :8080")     http.ListenAndServe(":8080", nil) }

You can run it directly with:

go run api-server.go

✅ Works without main.go.
✅ No need to rename — Go tools scan all .go files in the Directory (or specified paths) for the main package and main() function.
⚠️ Important: If you have multiple main packages in the same directory (e.g., server.go and cli.go, both with package main), go run . will fail with “multiple main packages”. Use go run server.go explicitly to avoid ambiguity.

Also note: For larger projects, especially web APIs, you’ll often separate concerns — e.g., main.go for bootstrapping, handlers/, models/, routes/ in other packages. while main.go remains idiomatic for clarity and tooling expectations (e.g., IDEs, CI linters), it’s purely a convention — not a language or toolchain requirement.

In summary: choose filenames that reflect intent (api.go, cmd/server.go, main.go) — but remember, Go only cares about package main + func main().