website·Indexed Apr 13, 2026
https://caddyserver.com/docs/Official documentation for Caddy, an open-source web server written in Go with automatic HTTPS. Covers Caddyfile and JSON configuration formats, admin API for runtime configuration, command-line interface, module/plugin architecture, reverse proxy and static file serving, TLS certificate management via ACME protocol with Let's Encrypt and ZeroSSL, Prometheus metrics, structured logging, and systemd deployment on Linux.
dynamic srv _api._tcp.example.com), load balancing policies (e.g., lb_policy least_conn), active/passive health checks with fail_duration and lb_try_duration, circuit breaking, retries, and graceful config changes. Example: reverse_proxy /api/* { dynamic srv _api._tcp.example.com } or reverse_proxy /service/* { to 10.0.1.1:80 10.0.1.2:80; lb_policy least_conn; lb_try_duration 10s; fail_duration 5s }.intercept directive intercepts and modifies HTTP responses before they reach the client. It is a generalized abstraction of the response interception feature from the reverse_proxy directive, and can be used with any handler that produces responses (e.g., FrankenPHP's php_server). The directive matches responses using response matchers; the first matching handle_response route or replace_status will be invoked. When invoked, the original response body is held back, giving the opportunity to write a different response body, new status code, or header manipulations. If the route does not write a new response body, the original response body is written instead.forward_auth directive offloads authentication to an external gateway by forwarding requests to a verification endpoint. It is an opinionated wrapper around reverse_proxy tailored for authentication use cases. If the upstream responds with a 2xx status code, access is granted and configured headers are copied to the original request. Any other status code causes the upstream's response (typically a redirect to a login page) to be returned to the client..sig signature file, and its .pem certificate file. Then decode the certificate and inspect it with OpenSSL.caddyfile.Unmarshaler interface on your module type. The interface gives you control over the Caddyfile syntax through how you parse tokens.localhost:2019. Change it via the CADDY_ADMIN environment variable or in the Caddy config (config takes precedence). The admin endpoint can be configured in the JSON config under admin {}. Configuration changes are saved to disk automatically unless disabled. Use caddy run --resume to restore the last working config after a restart.To redirect a specific path (e.g., /about-us) to a new path (/about) while handling other requests with another directive:
example.com {
redir /about-us /about
reverse_proxy localhost:9000
}example.com { redir /about-us /about reverse_proxy localhost:9000 }