@hendry It’s a bit difficult to compare the two. Kong is purely an API gateway/reverse proxy, whereas Caddy is primarily a web server, though it works just fine as reverse proxy. It’s been a while since I used Kong, but I remember it being awkward to configure and deploy, partly since it required a database to store its configuration (this is no longer required, but I believe still recommended in production).
As far as other differences, Kong is Lua running on top of OpenResty/nginx, whereas Caddy is pure Go.