Caddy Web Server

Caddy is an open-source web server and reverse proxy created by Matt Holt in 2015, providing automatic HTTPS through Let Us Encrypt certificate provisioning, HTTP/2 and HTTP/3 support, virtual hosting, reverse proxying, static file serving, TLS automation, and a clean configuration syntax, written in Go for simplicity and performance, designed to make web serving and TLS configuration effortless with zero-config automatic HTTPS by default, adopted by over forty thousand production deployments including Docker, Stripe, and HashiCorp for their web serving needs. The automatic HTTPS feature provisions and renews TLS certificates from the Let Us Encrypt and ZeroSSL certificate authorities without user intervention, with the server automatically detecting domain names from the configuration, requesting certificates on first start, renewing certificates before expiry, and handling HTTP-to-HTTPS redirects, while the on-demand TLS mode provisions certificates for arbitrary domains at request time, enabling dynamic virtual hosting without pre-configuration. The Caddyfile configuration syntax provides a human-readable format for defining site configurations, with each site block specifying the domain name, listen address, and directives for reverse proxy, file server, TLS settings, compression, header manipulation, authentication, rate limiting, and logging, while the JSON configuration provides a lower-level alternative for programmatic configuration and the admin API enables runtime configuration changes without restart. The modular architecture through plugins. The reverse proxy with health checks and load balancing. The HTTP/3 support through QUIC. The static file serving with pre-compressed assets. The request routing through matchers. The logging through structured JSON. The graceful reloads. Designed by Matt Holt. Designed for web operators.