Overview
Caddy is a modern web server written in Go, best known for automatic HTTPS: it obtains and renews TLS certificates from Let's Encrypt (or ZeroSSL) on its own, with no manual configuration. It works as a static file server, a reverse proxy, and a load balancer, and ships as a single dependency-free binary.
The Caddyfile
Configuration is typically a short, human-friendly Caddyfile. A reverse proxy can be as small as example.com { reverse_proxy localhost:8080 } — Caddy provisions the certificate automatically. JSON and an admin API are available for advanced use.
Command-line usage
The caddy binary is both server and tool: caddy run (foreground), caddy start / caddy stop, caddy reload (apply config without downtime), caddy fmt (format a Caddyfile), and caddy file-server / caddy reverse-proxy for ad-hoc use.