Caddy

Caddy is an extensible web server written in Go that provides TLS encryption by default for every site it serves, including public domains, localhost, and internal IP addresses. It automatically obtains and renews certificates from public authorities such as Let’s Encrypt and ZeroSSL, and can also operate a fully‑managed local certificate authority for internal use.

The server supports both a concise Caddyfile syntax and a native JSON configuration, which can be altered at runtime through a RESTful API. Features include on‑demand TLS for dynamic domains, multi‑issuer fallback, Encrypted ClientHello, and the ability to coordinate with other Caddy instances in a cluster, making it suitable for large‑scale deployments that require reliable TLS handling.

Caddy is released under the Apache‑2.0 license, is self‑hostable and free to use without subscription, and targets developers and enterprises that need a stable, open‑source solution for serving HTTPS‑enabled web applications and services.