caddy

Caddy is a web server that makes it easy to serve websites and applications over the internet with automatic HTTPS. The main problem it solves is the tedious setup usually required for SSL/TLS certificates (the technology that makes HTTPS work). Normally you have to manually request certificates from a certificate authority, configure your server to use them, and remember to renew them before they expire. Caddy does all of this automatically using services like Let's Encrypt and ZeroSSL, with no manual steps required.

Caddy works by reading a simple configuration file called a Caddyfile, where you declare your domain names, what content or application you want to serve, and any routing rules. It handles certificate issuance and renewal silently in the background. For more complex setups it also supports a JSON-based configuration and a live JSON API that lets you change configuration without restarting the server. It supports HTTP/1.1, HTTP/2, and HTTP/3 (the latest version of the web protocol, based on QUIC). Because it is written in Go, a single binary contains everything needed to run the server with no external dependencies, not even the C runtime library. It can be extended with plugins that add reverse proxying, load balancing, authentication, and other features.

You would use Caddy if you are self-hosting a website, API, or application on a server and want HTTPS to just work without manual certificate management. It is popular as a reverse proxy in front of other applications, and as a replacement for Nginx or Apache for simpler setups. The tech stack is Go, and deployment is typically a single downloaded binary. It runs on Linux, macOS, and Windows. The project is open-source and production-tested at large scale.