For Caddy we chose JSON because it's fairly universal, maps nearly 1:1 with Go structs (useful for initializing an extensible server), and nearly everything els

For Caddy we chose JSON because it's fairly universal, maps nearly 1:1 with Go structs (useful for initializing an extensible server), and nearly everything else compiles to JSON one way or another, so you can choose your own config format, really: https://caddyserver.com/docs/config-adapters https://caddyserver.com/docs/config-adapters