Caddy is a great, easy web server. It honestly has some pretty good performance too. If you want to see some good tests against nginx, take a look at this:
https://blog.tjll.net/reverse-proxy-hot-dog-eating-contest-caddy-vs-nginx/
tldr: Optimized nginx does outperform caddy in some areas in under heavy load, and they have a completely different strategies to handle failure. Under very heavy load Nginx just starts dropping and refusing connections to keep itself fast, while caddy will dramatically slow down response times in order to keep failures from happening.